Year Total 1965 15476000 1966 15172000 1967 15032000 1968 16331000 1969 15767000 1970 16928000 1971 16090000 1972 15183000 1973 15637000 1974 15888000 1975 15457000 1976 18300000 1977 23384000 1978 19228000 1979 18207000 1980 22175000 1981 22641000 1982 23925000 1983 25031000 1984 27882000 1985 26801000 1986 24839000 1987 26697000 1988 28669000 1989 28609000 1990 27137000 1991 26268000 1992 26759000 1993 23758000 1994 25191000 1995 26331000 1996 26881000 1997 28104000 1998 30055000 1999 28901000 2000 30588000 2001 31796000 2002 31992000 2003 31926000 2004 29997000 2005 30051000 2006 29164000 2007 30286000 2008 29399000 2009 23485000 2010 24766000 2011 21762000 2012 21050000 2013 20765000 2014 19731000 2015 19646000 2016 18677000