Year Number 1970 244000 1971 331100 1972 379000 1973 375700 1974 475000 1975 652500 1976 744700 1977 862300 1978 1015600 1979 1225500 1980 1342000 1981 1220300 1982 1160100 1983 1299000 1984 1359500 1985 1343300 1986 1300700 1987 1232600 1988 1266700 1989 1272600 1990 1237600 1991 1200000 1992 1214400 1993 1117000 1994 1175200 1995 1223700 1996 1783500 1997 2250800 1998 2115500 1999 1872600 2000 1756608 2001 1557128 2002 1508700 2003 1770774 2004 1824313 2005 1892343 2006 1443165 2007 1744663 2008 1718196 2009 1537032 2010 1781340 2011 2125912.52659794 2012 2206069.76066974 2013 2027888 2014 3563043.5828127 2015 4115271 2016 3678739 2017 4053427.35 2018 4122113 2019 4066959 2020 2627202.201 2021 4311879.56