| Year | Value | | 2024 | 89.344312287389 | | 2023 | 89.021844679612 | | 2022 | 89.038116455078 | | 2021 | 89.176204815324 | | 2020 | 88.930311496522 | | 2019 | 88.661815285712 | | 2018 | 88.165574957617 | | 2017 | 88.032047271729 | | 2016 | 88.102095858178 | | 2015 | 87.216710797254 | | 2014 | 83.602485074443 | | 2013 | 78.52183683847 | | 2012 | 73.778868023432 | | 2011 | 71.002872352833 | | 2010 | 69.347125394149 | | 2009 | 67.840143217122 | | 2008 | 66.513650890377 | | 2007 | 65.338961815469 | | 2006 | 64.287389393954 | | 2005 | 63.330247027387 | | 2004 | 62.438848117326 | | 2003 | 61.584506065326 | | 2002 | 60.738534272942 | | 2001 | 59.872246141732 | | 2000 | 58.97061200064 | | 1999 | 58.097276635734 | | 1998 | 57.290185731452 | | 1997 | 56.526666975621 | | 1996 | 55.790443886001 | | 1995 | 55.065239980354 | | 1994 | 54.334778776439 | | 1993 | 53.582783792016 | | 1992 | 52.792978544846 | | 1991 | 51.94908655269 | | 1990 | 51.031396034792 | | 1989 | 50.029758328222 | | 1988 | 48.95600695236 | | 1987 | 47.840272038811 | | 1986 | 46.710164235231 | | 1985 | 45.582834481705 | | 1984 | 44.422155060704 | | 1983 | 43.226387852897 | | 1982 | 42.042998735822 | | 1981 | 40.914455081179 | | 1980 | 39.884122006404 | | 1979 | 38.950321942612 | | 1978 | 38.078265631323 | | 1977 | 37.224488972568 | | 1976 | 36.347323423289 |
|