Year Number 1970 187100 1971 186500 1972 178200 1973 180600 1974 174400 1975 200500 1976 210200 1977 188500 1978 198400 1979 206900 1980 209300 1981 207700 1982 200600 1983 198200 1984 198600 1985 192800 1986 176500 1987 178500 1988 183300 1989 180200 1990 178500 1991 174100 1992 163700 1993 149400 1994 143800 1995 137800 1996 154100 1997 159000 1998 152500 1999 145800 2000 143612 2001 137114 2010 266822.2892449704 2011 307977.71707607375 2012 311610.2905595143 2013 329263.772 2014 346254.1529131582 2015 345543 2016 341547 2017 383488 2018 410069 2019 417461.09 2020 215962.91340000002 2021 325159.145