| Year | Value | | 2024 | 77.166492922828 | | 2023 | 77.125987229632 | | 2022 | 77.105606079102 | | 2021 | 77.098770141602 | | 2020 | 77.108032226562 | | 2019 | 77.072822570801 | | 2018 | 77.015632629395 | | 2017 | 76.960327148438 | | 2016 | 76.911582946777 | | 2015 | 76.87028503418 | | 2014 | 76.844245910645 | | 2013 | 76.81640625 | | 2012 | 76.777692006684 | | 2011 | 76.707663902788 | | 2010 | 76.609913246869 | | 2009 | 76.493025187113 | | 2008 | 76.365461375763 | | 2007 | 76.235683465059 | | 2006 | 76.11215310724 | | 2005 | 76.003331954549 | | 2004 | 75.917681659226 | | 2003 | 75.863663873511 | | 2002 | 75.85148911125 | | 2001 | 75.887565612793 | | 2000 | 75.635383605957 | | 1999 | 75.381683349609 | | 1998 | 75.310012817383 | | 1997 | 75.06763458252 | | 1996 | 74.784049987793 | | 1995 | 74.583229064941 | | 1994 | 74.508438110352 | | 1993 | 74.49486541748 | | 1992 | 74.414093017578 | | 1991 | 74.14485168457 | | 1990 | 73.727989196777 | | 1989 | 73.253379821777 | | 1988 | 72.67813873291 | | 1987 | 72.14591217041 | | 1986 | 71.577428130392 | | 1985 | 71.071884155273 | | 1984 | 70.820129394531 | | 1983 | 70.259872436523 | | 1982 | 69.523414611816 | | 1981 | 68.920738595345 | | 1980 | 68.405899047852 | | 1979 | 67.715912667979 | | 1978 | 66.878743487484 | | 1977 | 65.939290347179 | | 1976 | 64.942452087874 | | 1975 | 63.933127550381 |
|