Year | Value | 2021 | 2.8431084245494 | 2020 | 2.8431084245494 | 2019 | 2.8431084245494 | 2018 | 2.8431084245494 | 2017 | 2.8431084245494 | 2016 | 2.8431084245494 | 2015 | 2.8431084245494 | 2014 | 2.8104340249415 | 2013 | 2.7777596253335 | 2012 | 2.7450852257256 | 2011 | 2.7124108261177 | 2010 | 2.6797364265098 | 2009 | 2.6469178828142 | 2008 | 2.6142452624701 | 2007 | 2.5815726421259 | 2006 | 2.5490388280782 | 2005 | 2.5171869041782 | 2004 | 2.4845018249169 | 2003 | 2.4515496486737 | 2002 | 2.4163673957993 | 2001 | 2.3837196648166 | 2000 | 2.3510719338339 | 1999 | 2.3184242028512 | 1998 | 2.2857764718685 | 1997 | 2.2531287408858 | 1996 | 2.2204810099031 | 1995 | 2.1878332789205 | 1994 | 2.1551855479378 | 1993 | 2.1225378169551 | 1992 | 2.0898900859724 | 1991 | 2.0572423549897 | 1990 | 2.024594624007 |
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