Year Number 1970 2730800 1971 3045500 1972 3129100 1973 3816800 1974 3969800 1975 4109300 1976 4915900 1977 4914900 1978 5137300 1979 6108400 1980 6523600 1981 6950300 1982 7312600 1983 7409200 1984 7523200 1985 7444900 1986 7547000 1987 7658500 1988 8562800 1989 7604700 1990 7960400 1991 7140900 1992 7298800 1993 7175900 1994 7714900 1995 7254800 1996 7578500 1997 7529200 1998 7616900 1999 7515100 2000 7554646 2001 7411821 2002 7387912 2003 7524047 2004 9056444 2005 9802612 2006 10414732 2007 10839781 2008 11082489 2009 11608385 2010 17654275.920899734 2011 21331556.21601915 2012 22107026.960992195 2013 24484619.146003716 2014 25368159.471281476 2015 25261970 2016 26570744 2017 32239144.63031114 2018 38163132.40735727 2019 36727918.80994056 2020 17000506.794 2021 21246706.426