Cleaned up version of <a class="external free" href="https://commons.wikimedia.org/wiki/File:Playfair_TimeSeries.png">http://commons.wikimedia.org/wiki/File:Playfair_TimeSeries.png</a>
William Playfair (1759-1823)
Derivative work of <a class="external free" href="https://commons.wikimedia.org/wiki/File:Playfair_TimeSeries.png">http://commons.wikimedia.org/wiki/File:Playfair_TimeSeries.png</a>