Year	Number
1975	14482993
1976	14611222
1977	14424306
1978	14261635
1979	13861036
1980	13577609
1981	13343872
1982	13355605
1983	13615559
1984	14248273
1985	15042832
1986	16055961
1987	16998752
1988	17877148
1989	18055752
1990	18867120
1991	19039128
1992	19668384
1993	20033282
1994	20374096
1995	20139268
1996	21009180
1997	20214236
1998	20415386
1999	20667674
2000	19745768
2001	19021680
2002	18343012
2003	17410868
2004	16918816
2005	16007484
2006	15396773
2007	13757952
2008	13692464
2009	13840891
2010	14900000
2011	14200000
2012	14400000
2013	14300000
2014	14500000
2015	14800000
2016	15100000
2017	15200000
2018	15400000