Year Number 1960 33800 1961 33992 1962 34599 1963 35253 1964 35850 1965 36385 1966 36725 1967 37080 1968 37644 1969 38286 1970 38961 1971 39858 1972 40246 1973 40466 1974 41394 1975 42170 1976 42823 1977 43418 1978 43651 1979 44029 1980 44558 1981 45140 1982 45926 1983 46511 1984 46912 1985 47208 1986 47165 1987 46701 1988 45894 1989 45024 1990 44375 1991 43878 1992 43529 1993 43464 1994 43399 1995 43391 1996 43589 1997 43639 1998 42763 1999 41134 2000 39388 2001 37984 2002 38173 2003 39151 2004 40006 2005 41191 2006 42332 2007 43145 2008 43601 2009 43769 2010 44182 2011 44676 2012 45142 2013 45925 2014 46766 2015 47582 2016 48300 2017 48718 2018 51986 2019 53279 2020 51544 2021 50874 2022 50162 2023 49467