Year Number 1970 128800 1971 182700 1972 191500 1973 150000 1974 160000 1975 302100 1976 359300 1977 424800 1978 429600 1979 454600 1980 466300 1981 440300 1982 413900 1983 446700 1984 605000 1985 733600 1986 614500 1987 298700 1988 350500 1989 479500 1990 718000 1991 264200 1992 322900 1993 327900 1994 300200 1995 67400 1996 29500 1997 33600 1998 33500 1999 10400 2010 19167 2011 28232.1 2012 28442.05 2013 20004 2014 16128 2015 14463 2016 11903 2019 113752 2020 31391 2021 69447