Year Number 1970 4585300 1971 5013400 1972 5360200 1973 6261300 1974 6811800 1975 7320600 1976 8580400 1977 8761000 1978 9739500 1979 11291300 1980 13019500 1981 14210700 1982 14279000 1983 14397500 1984 14786200 1985 15179600 1986 14090900 1987 14322400 1988 14862300 1989 14713200 1990 14808400 1991 14208800 1992 13512500 1993 13923000 1994 14942600 1995 15368600 1996 16034300 1997 16477400 1998 16242300 1999 17122000 2000 17912857 2001 17173516 2002 16535011 2003 17883529 2004 20167567 2005 23620094 2006 25775571 2007 27232504 2008 28096606 2009 27748907 2010 38191509.13790186 2011 42648276.40103399 2012 45408840.802368455 2013 43790341.818 2014 44380996.11509803 2015 47850992 2016 49683303 2017 54260831.08 2018 64951730.360006236 2019 66236333.92023504 2020 24494981.601999998 2021 31483072.692000005