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	<g transform="translate(59,341)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 0</text>
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	<g transform="translate(59,305)" 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(59,268)" 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(59,232)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 30</text>
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	<g transform="translate(59,195)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 40</text>
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		<text> 50</text>
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	<g transform="translate(59,122)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 60</text>
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	<g transform="translate(59,86)" style="stroke:none; fill:black; font-family:sans-serif; font-size:12.00; text-anchor:end">
		<text> 70</text>
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	<path d='M76,45 L67,45 M782,45 L791,45 '></path>
	<g transform="translate(59,49)" 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:gray; stroke:currentColor; stroke-width:1.00">
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	<g transform="translate(59,13)" 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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	<path d='M94,337 L94,9 '></path>
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<g style="fill:none; color:gray; stroke:currentColor; stroke-width:1.00">
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		<text> 1960</text>
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	<path d='M275,337 L275,9 '></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='M275,337 L275,346 M275,9 L275,0 '></path>
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		<text> 1970</text>
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	<path d='M456,337 L456,9 '></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='M456,337 L456,346 M456,9 L456,0 '></path>
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		<text> 1980</text>
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	<path d='M637,337 L637,9 '></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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