| Year | Value | | 2024 | 99.321989172839 | | 2023 | 99.283532519383 | | 2022 | 99.243997525719 | | 2021 | 99.203408908243 | | 2020 | 99.161791383303 | | 2019 | 99.119169667207 | | 2018 | 99.075568476224 | | 2017 | 99.031012526598 | | 2016 | 98.985526534542 | | 2015 | 98.938240768115 | | 2014 | 98.901627838826 | | 2013 | 98.83576218279 | | 2012 | 98.742801047197 | | 2011 | 98.630061021091 | | 2010 | 98.506623216666 | | 2009 | 98.349488534095 | | 2008 | 98.129519393732 | | 2007 | 97.866312511174 | | 2006 | 97.582737879506 | | 2005 | 97.301665491817 | | 2004 | 97.047257955904 | | 2003 | 96.831118206401 | | 2002 | 96.642449759391 | | 2001 | 96.467430755172 | | 2000 | 96.294271892664 | | 1999 | 96.111183870782 | | 1998 | 95.906377388445 | | 1997 | 95.6663501955 | | 1996 | 95.388511968642 | | 1995 | 95.073686274088 | | 1994 | 94.722710548963 | | 1993 | 94.333906270384 | | 1992 | 93.905594915471 | | 1991 | 93.436097961342 | | 1990 | 92.923736885115 | | 1989 | 92.36683316391 | | 1988 | 91.763708274845 | | 1987 | 91.112683695039 | | 1986 | 90.423204054515 | | 1985 | 89.554543346102 | | 1984 | 88.328470554917 | | 1983 | 86.886958061484 | | 1982 | 85.403027629033 | | 1981 | 84.049701020795 | | 1980 | 83 | | 1979 | 82.223426412143 | | 1978 | 81.556525688325 | | 1977 | 80.972884970185 | | 1976 | 80.446091399365 |
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