Year	Number
1975	17067592
1976	17183930
1977	16865544
1978	16554141
1979	16043853
1980	15744345
1981	15454545
1982	15365637
1983	15684608
1984	16352419
1985	17295418
1986	18406494
1987	19513558
1988	20379016
1989	20865932
1990	21714724
1991	21797540
1992	22516200
1993	22902848
1994	23369992
1995	23884600
1996	25112998
1997	24228700
1998	24256508
1999	24096002
2000	23388980
2001	22662734
2002	22254588
2003	21163056
2004	20464956
2005	19561572
2006	18708148
2007	18026804
2008	17561368
2009	17552536
2010	18500000
2011	17800000
2012	17600000
2013	17600000
2014	17600000
2015	18200000
2016	18500000
2017	19000000
2018	19300000