Year Number 1970 40800 1971 40700 1972 41000 1973 40400 1974 37300 1975 36100 1976 39900 1977 42800 1978 46000 1979 48000 1980 47800 1981 43000 1982 40400 1983 39100 1984 40400 1985 43200 1986 45300 1987 45900 1988 51200 1989 59700 1990 66500 1991 70000 1992 77100 1993 109100 1994 118700 1995 141200 1996 164700 1997 182700 1998 213000 1999 233300 2000 225906 2001 178331 2002 133682 2003 132779 2004 154218 2005 151939 2006 158016 2007 173818 2008 179019 2009 249997 2010 127677.532209862 2011 131577 2012 132099.342541943 2013 130230 2014 132976.52964928 2015 141116 2016 147324 2017 145540 2018 140674 2019 137206.817 2020 57072.125 2021 73673.104