Year Number 1960 13106 1961 13414 1962 13759 1963 14119 1964 14504 1965 14898 1966 15305 1967 15757 1968 16238 1969 16723 1970 17197 1971 17566 1972 17858 1973 18169 1974 18488 1975 18810 1976 19128 1977 19446 1978 19777 1979 20115 1980 20434 1981 20736 1982 21054 1983 21391 1984 21728 1985 22066 1986 22412 1987 22766 1988 23137 1989 23518 1990 23896 1991 24262 1992 24630 1993 25015 1994 25403 1995 25799 1996 26232 1997 26689 1998 27136 1999 27588 2000 28029 2001 28382 2002 28671 2003 28951 2004 29225 2005 29503 2006 29766 2007 30008 2008 30242 2009 30495 2010 30730 2011 30974 2012 31260 2013 31530 2014 31786 2015 32012 2016 32230 2017 32465 2018 32707 2019 32952 2020 33169 2021 33390 2022 33610 2023 33798