Year Number 1970 558000 1971 513600 1972 762000 1973 968300 1974 1282500 1975 1835700 1976 3268000 1977 4705100 1978 6268100 1979 7689200 1980 9241200 1981 9146900 1982 10151800 1983 10670300 1984 11365800 1985 10795100 1986 9929400 1987 10258400 1988 9879600 1989 9988000 1990 10311500 1991 9409100 1992 11154800 1993 11864300 1994 12142300 1995 11524200 1996 11706300 1997 11738200 1998 11816200 1999 12328500 2000 12566492 2001 12835735 2002 13564300 2003 13821729 2004 14942633 2005 15933045 2006 16830838 2007 17141188 2008 16708204 2009 17508200 2010 20323592 2011 23135735 2012 26537661 2013 28252104 2014 32269452 2015 33431736 2016 35092840 2017 37503000 2018 39767648 2019 46181487 2020 20968865.89 2021 29403732