Year Number 1970 168900 1971 173200 1972 167600 1973 178100 1974 170500 1975 189900 1976 211000 1977 187300 1978 193800 1979 210100 1980 225400 1981 235300 1982 232000 1983 241100 1984 233200 1985 233000 1986 228600 1987 222000 1988 223800 1989 209300 1990 208400 1991 198400 1992 192600 1993 183800 1994 193400 1995 185000 1996 195600 1997 184700 1998 182300 1999 159200 2000 167795 2001 161861 2002 153359 2003 156369 2004 176521 2005 183126 2006 184038 2007 213090 2008 181228 2009 198073 2010 331174.8344430372 2011 379240.9494917603 2012 376331.9298692406 2013 430081.8152386171 2014 437496.1510407926 2015 412495 2016 426687 2017 520216 2018 581319.9644896858 2019 533290.3 2020 299967.93539999996 2021 349000.37000000005