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		<text> 0</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
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	<g transform="translate(59,294)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 2</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M76,243 L67,243 M782,243 L791,243 '></path>
	<g transform="translate(59,247)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 4</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M76,196 L67,196 M782,196 L791,196 '></path>
	<g transform="translate(59,200)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 6</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M76,150 L782,150 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M76,150 L67,150 M782,150 L791,150 '></path>
	<g transform="translate(59,154)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 8</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M76,103 L67,103 M782,103 L791,103 '></path>
	<g transform="translate(59,107)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 10</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M76,56 L67,56 M782,56 L791,56 '></path>
	<g transform="translate(59,60)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 12</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M76,9 L782,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M76,9 L67,9 M782,9 L791,9 '></path>
	<g transform="translate(59,13)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 14</text>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
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	<g transform="translate(76,368)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:middle">
		<text> 1930</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M181,337 L181,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M181,337 L181,346 M181,9 L181,0 '></path>
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		<text> 1940</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M287,337 L287,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M287,337 L287,346 M287,9 L287,0 '></path>
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		<text> 1950</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M392,337 L392,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
</g>
<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M392,337 L392,346 M392,9 L392,0 '></path>
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		<text> 1960</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M497,337 L497,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M497,337 L497,346 M497,9 L497,0 '></path>
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		<text> 1970</text>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M603,337 L603,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:1.00">
	<path d='M603,337 L603,346 M603,9 L603,0 '></path>
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		<text> 1980</text>
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	<path d='M708,337 L708,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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	<path d='M708,337 L708,346 M708,9 L708,0 '></path>
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		<text> 1990</text>
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		<text>Number of references</text>
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		<text>Year of publication</text>
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