| Year | Value | | 2020 | 0.72949086907197 | | 2019 | 0.72310582547179 | | 2018 | 0.73174026609423 | | 2017 | 0.7271425497669 | | 2016 | 0.73215599730889 | | 2015 | 0.73633861489039 | | 2014 | 0.7374292407102 | | 2013 | 0.74166726656472 | | 2012 | 0.7835080475011 | | 2011 | 0.78726744192602 | | 2010 | 0.79512064803713 | | 2009 | 0.8020141895294 | | 2008 | 0.79805594182653 | | 2007 | 0.79820743348911 | | 2006 | 0.86824883336342 | | 2005 | 0.86679301401885 | | 2004 | 0.84261766039708 | | 2003 | 0.87420586810437 | | 2002 | 0.88523361857587 | | 2001 | 0.89912069154098 | | 2000 | 0.93192429485633 | | 1999 | 0.94601350925646 | | 1998 | 0.98736449440473 | | 1997 | 1.0036591814425 | | 1996 | 1.0390015292876 | | 1995 | 1.0503893360284 | | 1994 | 0.76438802522653 | | 1993 | 0.7947863503213 | | 1992 | 0.85101398356392 | | 1991 | 0.7975580667297 |
|