Year Number 1970 2247818 1971 2314790 1972 2474526 1973 2608284.5 1974 2704155 1975 2819910.25 1976 2945940.5 1977 3093010.25 1978 3237399 1979 3412357.75 1980 3589063.75 1981 3780078 1982 3976616.5 1983 4306780 1984 4521823.5 1985 4793641.5 1986 5024290 1987 5258483.5 1988 5438399 1989 5544165 1990 5844479 1991 6066793.5 1992 6249032 1993 6445769.5 1994 6635385 1995 6817470 1996 7008781 1997 7236272.5 1998 7347267.5 1999 7434117.5 2000 7723160.5 2001 7902957 2002 8327938.5 2003 8698970 2004 8908020 2005 9494669 2006 10013616 2007 10576613 2008 11208584 2009 11629313 2010 12085002 2011 12163563 2012 11971335 2013 12028122 2014 12485734 2015 12845779 2016 13683318 2017 13847977 2018 14716131 2019 15604258 2020 16230158 2021 16331421 2022 16435180