Year Number 1970 6743700 1971 7644100 1972 7462200 1973 8189900 1974 8631400 1975 8360600 1976 8238100 1977 9424100 1978 9507000 1979 9462500 1980 9955800 1981 10493300 1982 11611000 1983 11996600 1984 12593600 1985 14408000 1986 13811100 1987 15268100 1988 15649200 1989 17437700 1990 19750000 1991 18846800 1992 21766700 1993 21901400 1994 22959300 1995 23665800 1996 25838500 1997 28183900 1998 27462700 1999 28281000 2000 30418137 2001 31031074 2002 28244627 2003 36345771 2004 35922093 2005 36115764 2006 36709131 2007 37830745 2008 30672048 2009 33194501 2010 32645164 2011 33923370.5051058 2012 31072962.155732 2013 27846220 2014 27193939 2015 28603919 2016 29120041 2017 26288001 2018 27243741 2019 27760301 2020 7801490 2021 2449339