| Year | Value | | 2024 | 19,376 | | 2023 | 19,030 | | 2022 | 20,090 | | 2021 | 19,954 | | 2020 | 23,421 | | 2019 | 23,242 | | 2018 | 23,857 | | 2017 | 24,669 | | 2016 | 25,130 | | 2015 | 24,894 | | 2014 | 23,634 | | 2013 | 22,312 | | 2012 | 21,654 | | 2011 | 22,258 | | 2010 | 24,145 | | 2009 | 26,555 | | 2008 | 26,691 | | 2007 | 25,788 | | 2006 | 23,516 | | 2005 | 22,272 | | 2004 | 22,834 | | 2003 | 23,598 | | 2002 | 23,879 | | 2001 | 23,948 | | 2000 | 23,902 | | 1999 | 23,819 | | 1998 | 23,765 | | 1997 | 23,857 | | 1996 | 24,396 | | 1995 | 25,337 | | 1994 | 26,358 | | 1993 | 27,455 | | 1992 | 28,623 | | 1991 | 29,856 | | 1990 | 31,148 | | 1989 | 32,490 | | 1988 | 33,873 | | 1987 | 35,283 | | 1986 | 36,624 | | 1985 | 38,224 | | 1984 | 40,603 | | 1983 | 43,235 | | 1982 | 45,475 | | 1981 | 46,823 | | 1980 | 46,905 | | 1979 | 45,983 | | 1978 | 44,598 | | 1977 | 42,865 | | 1976 | 40,878 |
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