Year Number 1970 8147600 1971 8263700 1972 8254700 1973 8409000 1974 7796100 1975 7633500 1976 7824900 1977 8158300 1978 8367500 1979 8666100 1980 8640600 1981 8176300 1982 8193100 1983 8508000 1984 8971400 1985 9443800 1986 10152300 1987 10633200 1988 11155300 1989 11302500 1990 11832500 1991 11517500 1992 11936900 1993 12024600 1994 13152600 1995 13849900 1996 14663400 1997 15188600 1998 15371000 1999 16409600 2000 17624505 2001 17392600 2002 16063702 2003 16602403 2004 18407015 2005 18709113 2006 18809257 2007 19348839 2008 18688257 2009 18650104 2010 20927396.79163628 2011 21094558.129246823 2012 20984277.381897546 2013 21039809.2984916 2014 21081416.36764928 2015 21455548 2016 22020267 2017 22182317.92 2018 22460256.787081297 2019 22822190.733 2020 11609007.87 2021 14702405.542