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	<g transform="translate(67,341)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 0</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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	<g transform="translate(67,308)" 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 transform="translate(67,275)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 20</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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	<g transform="translate(67,243)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 30</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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	<path d='M84,206 L782,206 '></path>
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	<path d='M84,206 L75,206 M782,206 L791,206 '></path>
	<g transform="translate(67,210)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 40</text>
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	<path d='M84,173 L782,173 '></path>
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	<path d='M84,173 L75,173 M782,173 L791,173 '></path>
	<g transform="translate(67,177)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 50</text>
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	<path d='M84,140 L75,140 M782,140 L791,140 '></path>
	<g transform="translate(67,144)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 60</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:black; stroke:currentColor; stroke-width:1.00">
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	<g transform="translate(67,111)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 70</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">
	<path d='M84,75 L75,75 M782,75 L791,75 '></path>
	<g transform="translate(67,79)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 80</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
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	<path d='M84,42 L782,42 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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	<path d='M84,42 L75,42 M782,42 L791,42 '></path>
	<g transform="translate(67,46)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 90</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='M84,9 L782,9 '></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='M84,9 L75,9 M782,9 L791,9 '></path>
	<g transform="translate(67,13)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 100</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
</g>
<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M175,337 L175,9 '></path>
</g>
<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='M175,337 L175,346 M175,9 L175,0 '></path>
	<g transform="translate(175,368)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:middle">
		<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='M276,337 L276,9 '></path>
</g>
<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='M276,337 L276,346 M276,9 L276,0 '></path>
	<g transform="translate(276,368)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:middle">
		<text> 1950</text>
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<g style="fill:none; color:black; stroke:currentColor; stroke-width:0.20">
</g>
<g style="fill:none; color:gray; stroke:currentColor; stroke-width:0.20">
	<path d='M377,337 L377,9 '></path>
</g>
<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='M377,337 L377,346 M377,9 L377,0 '></path>
	<g transform="translate(377,368)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:middle">
		<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='M479,337 L479,9 '></path>
</g>
<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='M479,337 L479,346 M479,9 L479,0 '></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='M580,337 L580,9 '></path>
</g>
<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='M580,337 L580,346 M580,9 L580,0 '></path>
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		<text> 1980</text>
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	<path d='M681,337 L681,9 '></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='M681,337 L681,346 M681,9 L681,0 '></path>
	<g transform="translate(681,368)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:middle">
		<text> 1990</text>
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	<path d='M782,337 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='M782,337 L782,346 M782,9 L782,0 '></path>
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		<text> 2000</text>
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	<path d='M84,337 L782,337 L782,9 L84,9 L84,337 '></path>
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		<text>Number of references</text>
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		<text>Year of publication</text>
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