| Year | Value | | 2020 | 0.90327708927991 | | 2019 | 0.84961045360702 | | 2018 | 0.55945018956754 | | 2017 | 0.4368605453767 | | 2016 | 0.57698794539031 | | 2015 | 0.58603963431127 | | 2014 | 0.59497112101713 | | 2013 | 0.6046230407888 | | 2012 | 0.40111935896407 | | 2011 | 0.40866759939036 | | 2010 | 0.42165543886486 | | 2009 | 0.42954253719788 | | 2008 | 0.50631629578998 | | 2007 | 0.442184390891 | | 2006 | 0.45004500450045 | | 2005 | 0.4584099570907 | | 2004 | 0.46702326970594 | | 2003 | 0.49718537833045 | | 2002 | 0.50530003593245 | | 2001 | 1.8311140612393 | | 2000 | 1.8700545822181 | | 1999 | 1.9118174214362 | | 1998 | 1.9373666527699 | | 1997 | 1.9724112102865 | | 1996 | 2.0461666346953 | | 1995 | 1.3742286323807 |
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