Year Number 1970 84429.91 1971 88743.91 1972 94561.7 1973 99637.68 1974 106657.4 1975 112518.7 1976 118113.6 1977 122952.1 1978 125830.8 1979 128792.6 1980 130950.7 1981 131554 1982 134148.5 1983 135154.3 1984 135313.7 1985 133126.5 1986 133154.9 1987 135754.4 1988 136905.4 1989 138313.1 1990 140529.4 1991 152998.1 1992 160141.1 1993 164989.8 1994 169339.3 1995 174105.2 1996 177099.6 1997 184582.7 1998 185224.2 1999 189261.7 2000 185317.8 2001 188696.5 2002 197228.1 2003 201218.5 2004 202983.3 2005 202574.8 2006 209329.1 2007 209913.8 2008 214380.5 2009 222534.1 2010 231773.8 2011 233522.2 2012 232428.5 2013 232111.7 2014 231866.2 2015 232192.7 2016 233637.4 2017 236517.1 2018 240332