Year Number 1970 9013411 1971 9252995 1972 9833470 1973 10257471 1974 10644102 1975 11042869 1976 11415553 1977 11597076 1978 11620041 1979 11815722 1980 12260470 1981 12634536 1982 13021613 1983 13359428 1984 13614001 1985 13792619 1986 14053572 1987 14219913 1988 14527909 1989 15025388 1990 15179950 1991 15309269 1992 15437911 1993 15670406 1994 15873080 1995 16055666 1996 16209798 1997 16386151 1998 16452516 1999 16640123 2000 16694290 2001 16776988 2002 16672460 2003 17129216 2004 17639704 2005 17713198 2006 17843602 2007 18223450 2008 18230156 2009 18389286 2010 18569650 2011 18621574 2012 18934976 2013 19508762 2014 19572120 2015 19837204 2016 20242852 2017 19926436 2018 19874026 2019 20477570 2020 20758934 2021 21028528 2022 21043196