| Year | Value | | 2021 | 41,986.232859588 | | 2020 | 34,953.036361061 | | 2019 | 37,785.727608927 | | 2018 | 37,828.31685725 | | 2017 | 36,906.311717109 | | 2016 | 34,318.544923717 | | 2015 | 35,364.119107178 | | 2014 | 41,608.03614682 | | 2013 | 43,054.542645188 | | 2012 | 43,024.450803671 | | 2011 | 42,617.974060283 | | 2010 | 38,678.180586557 | | 2009 | 32,986.048104979 | | 2008 | 37,787.147044502 | | 2007 | 36,533.91745951 | | 2006 | 33,132.788630699 | | 2005 | 29,229.897191355 | | 2004 | 26,003.164647179 | | 2003 | 22,686.553972543 | | 2002 | 19,537.081005585 | | 2001 | 18,986.182940375 | | 2000 | 19,386.445409693 | | 1999 | 17,868.200033476 | | 1998 | 16,794.229268229 | | 1997 | 17,542.888960406 | | 1996 | 17,002.699841705 | | 1995 | 16,619.926578407 | | 1994 | 16,017.944157 | | 1993 | 16,170.209939432 | | 1992 | 16,735.091101731 | | 1991 | 17,586.476602072 | | 1990 | 17,207.343172986 | | 1989 | 16,740.828939883 | | 1988 | 15,354.498047789 | | 1987 | 13,252.829639081 | | 1986 | 11,704.987163297 | | 1985 | 11,332.258972115 | | 1984 | 11,097.10982405 | | 1983 | 10,706.574850716 | | 1982 | 9,873.0779070175 | | 1981 | 9,752.9384584914 | | 1980 | 8,745.6048211327 | | 1979 | 7,922.7628409308 | | 1978 | 7,439.3067452062 | | 1977 | 7,288.6314121786 | | 1976 | 7,231.9245974874 |
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