Year	Number
1971	758900
1972	787400
1973	808300
1974	822877
1975	813517
1976	796569
1977	768510
1978	735597
1979	702700
1980	674200
1981	642000
1982	615300
1983	598700
1984	590500
1985	586700
1986	586200
1987	586400
1988	585000
1989	585800
1990	582600
1991	843700
1992	847600
1993	851100
1994	867500
1995	902100
1996	929000
1997	946100
1998	965900
1999	971888
2000	995611
2001	986673
2002	977082
2003	993016
2004	965135
2005	923798
2006	873131
2007	817820
2008	772562
2009	721131
2010	648875
2011	608469
2012	586324
2013	572580
2014	562517
2015	559067
2016	558596
2017	559300
2018	566765