Year Number 1970 146900 1971 159400 1972 167300 1973 176400 1974 178800 1975 181800 1976 184500 1977 192700 1978 209300 1979 214200 1980 207900 1981 188700 1982 191000 1983 194000 1984 184900 1985 181700 1986 180400 1987 183000 1988 207200 1989 225500 1990 244700 1991 262600 1992 289700 1993 282200 1994 282300 1995 313200 1996 332800 1997 370400 1998 387900 1999 414200 2000 485856 2001 517481 2002 493019 2003 518836 2004 549963 2005 586438 2006 602978 2007 657606 2008 616893 2009 547971 2010 546298.853885983 2011 535074 2012 471440.886886395 2013 465558.909 2014 486353.8 2015 534895 2016 566775 2017 579842 2018 641097 2019 677578.545 2020 261972.271 2021 381188.363