Year Number 1970 390500 1971 263700 1972 525300 1973 590000 1974 1116900 1975 1335200 1976 1439200 1977 1425000 1978 1449000 1979 1686100 1980 1980100 1981 1777100 1982 1739700 1983 1698200 1984 1616800 1985 1563900 1986 2152900 1987 3009000 1988 2737100 1989 1854300 1990 1816200 1991 1490600 1992 1217600 1993 1362400 1994 1894900 1995 2508300 1996 2327500 1997 2724500 1998 2774500 1999 1900000 2000 1595268 2001 2248991 2002 2085823 2003 2226329 2004 3225128 2005 4332223 2006 4217880 2007 5273188 2008 6184410 2009 5843195 2010 7106025.29251721 2011 8609620.35441221 2012 10074855.6119232 2013 12255937.7629497 2014 12284677 2015 13877662 2016 15081755 2017 16094150 2018 17758527.272 2019 18820572 2020 5705074 2021 9053965