Year Number 1970 220000 1971 228000 1972 224700 1973 228200 1974 220100 1975 253200 1976 279800 1977 260600 1978 274000 1979 299000 1980 319400 1981 332600 1982 317200 1983 323100 1984 316800 1985 321700 1986 288600 1987 291800 1988 285800 1989 296600 1990 301300 1991 305600 1992 296300 1993 289100 1994 290100 1995 264900 1996 276400 1997 319700 1998 313400 1999 319300 2000 335069 2001 328777 2002 297804 2003 319863 2004 337379 2005 360846 2006 358736 2007 400752 2008 354861 2009 361975 2010 578696.6200196506 2011 624597.4444942056 2012 649833.2497254367 2013 689280.772 2014 665781.1268037994 2015 703831 2016 701537 2017 760811 2018 843583.211146022 2019 857966.0900000001 2020 370198.54639999993 2021 525625.861