Year Number 1960 42387 1961 43439 1962 44439 1963 45419 1964 46374 1965 47307 1966 48203 1967 49048 1968 49822 1969 50532 1970 51023 1971 51297 1972 51533 1973 51731 1974 51906 1975 52186 1976 52589 1977 53019 1978 53466 1979 53922 1980 54387 1981 54800 1982 55153 1983 55521 1984 55919 1985 56308 1986 56631 1987 56879 1988 57063 1989 57166 1990 57138 1991 57007 1992 56641 1993 56005 1994 55306 1995 54583 1996 53833 1997 53043 1998 52232 1999 51499 2000 50721 2001 49756 2002 48759 2003 47813 2004 46888 2005 45953 2006 44981 2007 43995 2008 43046 2009 42169 2010 41142 2011 39967 2012 38905 2013 37970 2014 37106 2015 36264 2016 35486 2017 34832 2018 34276 2019 33763 2020 33290 2021 32865 2022 32444 2023 31988