| Year | Value | | 2022 | 19,169 | | 2021 | 18,114 | | 2020 | 17,417 | | 2019 | 16,394 | | 2018 | 15,266 | | 2017 | 14,407 | | 2016 | 13,750 | | 2015 | 13,228 | | 2014 | 12,912 | | 2013 | 12,835 | | 2012 | 12,970 | | 2011 | 13,281 | | 2010 | 13,842 | | 2009 | 14,382 | | 2008 | 14,665 | | 2007 | 14,874 | | 2006 | 15,055 | | 2005 | 15,072 | | 2004 | 14,940 | | 2003 | 14,831 | | 2002 | 14,599 | | 2001 | 14,293 | | 2000 | 14,068 | | 1999 | 14,040 | | 1998 | 14,188 | | 1997 | 14,487 | | 1996 | 14,848 | | 1995 | 15,108 | | 1994 | 15,076 | | 1993 | 14,823 | | 1992 | 14,149 | | 1991 | 12,895 | | 1990 | 11,406 | | 1989 | 10,332 | | 1988 | 9,437 | | 1987 | 8,916 | | 1986 | 8,814 | | 1985 | 8,759 | | 1984 | 8,678 | | 1983 | 8,680 | | 1982 | 8,536 | | 1981 | 8,325 | | 1980 | 8,182 | | 1979 | 7,995 | | 1978 | 7,821 | | 1977 | 7,656 | | 1976 | 7,587 | | 1975 | 7,588 | | 1974 | 7,638 | | 1973 | 7,768 | | 1972 | 7,880 | | 1971 | 7,932 | | 1970 | 7,898 | | 1969 | 7,834 | | 1968 | 7,757 | | 1967 | 7,621 | | 1966 | 7,434 | | 1965 | 7,226 | | 1964 | 7,017 | | 1963 | 6,853 | | 1962 | 6,790 | | 1961 | 6,836 | | 1960 | 6,985 |
|