| Year | Value | | 2022 | 19,718 | | 2021 | 18,947 | | 2020 | 18,175 | | 2019 | 17,198 | | 2018 | 16,438 | | 2017 | 16,594 | | 2016 | 17,400 | | 2015 | 17,726 | | 2014 | 18,161 | | 2013 | 18,438 | | 2012 | 17,732 | | 2011 | 16,835 | | 2010 | 15,632 | | 2009 | 14,510 | | 2008 | 13,630 | | 2007 | 12,692 | | 2006 | 11,780 | | 2005 | 10,933 | | 2004 | 10,162 | | 2003 | 9,477 | | 2002 | 8,866 | | 2001 | 8,297 | | 2000 | 7,747 | | 1999 | 7,227 | | 1998 | 6,983 | | 1997 | 6,804 | | 1996 | 6,489 | | 1995 | 6,229 | | 1994 | 5,913 | | 1993 | 5,654 | | 1992 | 5,510 | | 1991 | 5,319 | | 1990 | 5,088 | | 1989 | 4,961 | | 1988 | 5,293 | | 1987 | 5,609 | | 1986 | 5,467 | | 1985 | 5,254 | | 1984 | 5,058 | | 1983 | 4,864 | | 1982 | 4,659 | | 1981 | 4,464 | | 1980 | 4,295 | | 1979 | 4,158 | | 1978 | 4,049 | | 1977 | 3,960 | | 1976 | 3,900 | | 1975 | 3,852 | | 1974 | 3,805 | | 1973 | 3,759 | | 1972 | 3,741 | | 1971 | 3,764 | | 1970 | 3,852 | | 1969 | 4,005 | | 1968 | 4,163 | | 1967 | 4,318 | | 1966 | 4,489 | | 1965 | 4,621 | | 1964 | 4,655 | | 1963 | 4,689 | | 1962 | 4,724 | | 1961 | 4,715 | | 1960 | 4,695 |
|