Year | Value | 2021 | 15.574991218827 | 2020 | 15.595363540569 | 2019 | 15.623463294696 | 2018 | 15.651563048823 | 2017 | 15.665612925887 | 2016 | 15.67966280295 | 2015 | 15.690200210748 | 2014 | 15.718299964875 | 2013 | 15.742887249737 | 2012 | 15.749912188268 | 2011 | 15.778011942395 | 2010 | 15.753424657534 | 2009 | 15.785036880927 | 2008 | 15.820161573586 | 2007 | 15.879873551106 | 2006 | 15.907973305234 | 2005 | 15.981735159817 | 2004 | 15.981735159817 | 2003 | 15.981735159817 | 2002 | 15.981735159817 | 2001 | 15.981735159817 | 2000 | 15.806111696523 | 1999 | 15.806111696523 | 1998 | 15.981735159817 | 1997 | 15.981735159817 | 1996 | 15.806111696523 | 1995 | 15.279241306639 | 1994 | 15.279241306639 | 1993 | 15.208991921321 | 1992 | 14.857744994731 |
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