<a href="https://en.wikipedia.org/wiki/Time_series" class="extiw" title="en:Time series">Time series</a> of <a href="https://en.wikipedia.org/wiki/atmosphere" class="extiw" title="en:atmosphere">atmospheric</a> concentrations of <a href="https://en.wikipedia.org/wiki/CFC-12" class="extiw" title="en:CFC-12">CFC-12</a> from 1931 to 2003.  Mixing ratio concentrations are shown for the <a href="https://en.wikipedia.org/wiki/Northern_hemisphere" class="extiw" title="en:Northern hemisphere">northern</a> and <a href="https://en.wikipedia.org/wiki/Southern_hemisphere" class="extiw" title="en:Southern hemisphere">southern</a> hemispheres, and are expressed as <a href="https://en.wikipedia.org/wiki/Parts-per_notation" class="extiw" title="en:Parts-per notation">parts per trillion</a>.  The dotted line at 1989 incidates the time at which the <a href="https://en.wikipedia.org/wiki/Montreal_Protocol" class="extiw" title="en:Montreal Protocol">Montreal Protocol on Substances That Deplete the Ozone Layer</a> came into force.  The data are plotted here using <a href="https://en.wikipedia.org/wiki/MATLAB" class="extiw" title="en:MATLAB">MATLAB</a>.
<p>The <a href="https://en.wikipedia.org/wiki/scientific_literature" class="extiw" title="en:scientific literature">published</a> source of data for the figure is: 
</p><p>Walker, S. J., R. F. Weiss &amp; P. K. Salameh (2000) Reconstructed histories of the annual mean atmospheric mole fractions for the halocarbons CFC-11, CFC-12, CFC-113 and carbon tetrachloride. <i>Journal of Geophysical Research</i> <b>105</b>, 14285—14296.
</p>
The data (including error estimates and updates) are available online from the <a rel="nofollow" class="external text" href="http://bluemoon.ucsd.edu/pub/cfchist/">atmospheric halocarbon page</a> at <a href="https://en.wikipedia.org/wiki/University_of_California,_San_Diego" class="extiw" title="en:University of California, San Diego">University of California</a>.
<a href="//commons.wikimedia.org/wiki/User:%D0%94.%D0%98%D0%BB%D1%8C%D0%B8%D0%BD" title="User:Д.Ильин">Д.Ильин</a>: vectorization, translation
<a href="//commons.wikimedia.org/wiki/File:AYool_CFC-12_history.png" title="File:AYool CFC-12 history.png">File:AYool CFC-12 history.png</a> by <a href="https://en.wikipedia.org/wiki/User:Plumbago" class="extiw" title="wikipedia:User:Plumbago">Plumbago</a> at <a href="https://en.wikipedia.org/wiki/" class="extiw" title="wikipedia:">English Wikipedia</a>