| Year | Value | | 2019 | 4,872 | | 2018 | 4,667 | | 2017 | 4,452 | | 2016 | 4,258 | | 2015 | 4,109 | | 2014 | 4,158 | | 2013 | 4,215 | | 2012 | 4,246 | | 2011 | 4,248 | | 2010 | 4,251 | | 2009 | 4,299 | | 2008 | 4,429 | | 2007 | 4,608 | | 2006 | 4,770 | | 2005 | 4,852 | | 2004 | 4,898 | | 2003 | 4,889 | | 2002 | 4,847 | | 2001 | 4,802 | | 2000 | 4,750 | | 1999 | 4,583 | | 1998 | 4,436 | | 1997 | 4,330 | | 1996 | 4,300 | | 1995 | 4,357 | | 1994 | 4,543 | | 1993 | 4,879 | | 1992 | 5,303 | | 1991 | 5,693 | | 1990 | 5,944 | | 1989 | 5,852 | | 1988 | 5,639 | | 1987 | 5,376 | | 1986 | 5,140 | | 1985 | 4,951 | | 1984 | 4,715 | | 1983 | 4,520 | | 1982 | 4,377 | | 1981 | 4,288 | | 1980 | 4,221 | | 1979 | 4,088 | | 1978 | 3,950 | | 1977 | 3,820 | | 1976 | 3,701 | | 1975 | 3,589 | | 1974 | 3,513 | | 1973 | 3,489 | | 1972 | 3,499 | | 1971 | 3,515 | | 1970 | 3,508 | | 1969 | 3,428 | | 1968 | 3,337 | | 1967 | 3,238 | | 1966 | 3,152 | | 1965 | 3,090 | | 1964 | 2,996 | | 1963 | 2,915 | | 1962 | 2,842 | | 1961 | 2,764 | | 1960 | 2,683 |
|