Year	Number
1970	13410578
1971	13753028
1972	13888765
1973	13658062
1974	14147527
1975	14151850
1976	14021542
1977	14190183
1978	14485537
1979	14376602
1980	14088257
1981	13792207
1982	14273080
1983	14127496
1984	14261768
1985	14651740
1986	14736530
1987	15540264
1988	15840971
1989	16590202
1990	17765216
1991	16803724
1992	17414340
1993	17805156
1994	17895300
1995	17894028
1996	18852944
1997	19698738
1998	20937128
1999	21905354
2000	21736136
2001	21197908
2002	20616722
2003	19805718
2004	19391704
2005	19219446
2006	18496292
2007	18323840
2008	16884952
2009	16946970
2010	16700000
2011	16500000
2012	16000000
2013	16500000
2014	16100000
2015	16500000
2016	16500000
2018	16900000