Year Total 1970 9415000 1971 15646000 1972 22576000 1973 24512000 1974 29562000 1975 30783000 1976 32599000 1977 34061000 1978 32617000 1979 32936000 1980 31311000 1981 31241000 1982 31753000 1983 32741000 1984 32007000 1985 35711000 1986 37545000 1987 39307000 1988 37853000 1989 37069000 1990 40932000 1991 45574000 1992 46345000 1993 54488000 1994 58172000 1995 63679000 1996 75732000 1997 77272000 1998 81145000 1999 89177000 2000 97537000 2001 95243000 2002 93245000 2003 92642000 2004 86723000 2005 79353000 2006 71965000 2007 64868000 2008 62667000 2009 53713000 2010 51421000 2011 40715000 2012 34992000 2013 32829000 2014 33110000 2015 35625000 2016 36900000