Year	Number
1973	11685702
1974	11590837
1975	11524725
1976	11475141
1977	11196640
1978	10811120
1979	10331196
1980	10263840
1981	10268034
1982	10470825
1983	10625939
1984	11030578
1985	11645174
1986	12464743
1987	13286979
1988	14006297
1989	14746377
1990	15272339
1991	15452593
1992	16032160
1993	16298305
1994	16613689
1995	16461672
1996	17581410
1997	16856000
1998	17189440
1999	17508380
2000	16978316
2001	16338115
2002	15388405
2003	14238920
2004	13772398
2005	13572828
2006	13193916
2007	12056893
2008	12407407
2009	12469619
2010	13300000
2011	13100000
2012	13300000
2013	13700000
2014	13800000
2015	14200000
2016	14400000
2017	14700000
2018	14800000