| Year | Value | | 2021 | 40,517.452831682 | | 2020 | 34,536.817159185 | | 2019 | 35,420.775325485 | | 2018 | 35,119.883856037 | | 2017 | 35,289.260939329 | | 2016 | 33,030.983676219 | | 2015 | 31,702.730372189 | | 2014 | 36,328.597632336 | | 2013 | 35,087.22424484 | | 2012 | 32,281.409692635 | | 2011 | 30,794.530891935 | | 2010 | 26,700.636622787 | | 2009 | 22,466.356473932 | | 2008 | 23,867.851209317 | | 2007 | 25,405.150743527 | | 2006 | 20,882.772717638 | | 2005 | 21,955.7866346 | | 2004 | 20,395.305923407 | | 2003 | 17,792.467527522 | | 2002 | 13,539.773575913 | | 2001 | 11,055.345656111 | | 2000 | 10,713.477088459 | | 1999 | 12,131.406202798 | | 1998 | 11,834.418811941 | | 1997 | 13,802.093918712 | | 1996 | 14,579.048900256 | | 1995 | 13,729.90505182 | | 1994 | 11,943.264448967 | | 1993 | 10,110.217733809 | | 1992 | 9,109.1033301889 | | 1991 | 9,441.3849218307 | | 1990 | 10,966.620434557 | | 1989 | 10,759.449897492 | | 1988 | 11,164.038571084 | | 1987 | 9,818.1310483956 | | 1986 | 7,462.5596409852 | | 1985 | 5,903.8656630041 | | 1984 | 5,295.7933630813 | | 1983 | 6,105.8633026106 | | 1982 | 6,182.7597705496 | | 1981 | 6,356.5201830755 | | 1980 | 6,063.7736579579 | | 1979 | 5,372.9327355643 | | 1978 | 4,756.6597267446 | | 1977 | 3,969.7054674312 | | 1976 | 3,552.6033002074 | | 1975 | 3,431.0220036566 | | 1974 | 3,967.9720228062 | | 1973 | 3,781.1975705494 | | 1972 | 2,877.5202766827 | | 1971 | 2,430.2167046767 |
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