Year	Number
1970	7393989
1971	7494898
1972	7783290
1973	7891374
1974	8115655
1975	8122878
1976	8539078
1977	8789899
1978	8967036
1979	9200980
1980	9312625
1981	9364485
1982	9522481
1983	9603995
1984	9459916
1985	9382250
1986	9705941
1987	9623443
1988	9469806
1989	9261729
1990	8965896
1991	8976661
1992	9099141
1993	9253011
1994	9849511
1995	9738655
1996	9647973
1997	9207153
1998	7529047
1999	7434694
2000	6392503
2001	6555739
2002	6656215
2003	6604104
2004	7915461
2005	8111982
2006	7632679
2007	7594763
2008	7650910
2009	7451562
2010	7530413
2011	7473727
2012	7345588
2013	7094731
2014	6937312
2015	6865455
2016	6847218
2017	6866506
2018	6884519