Year	Number
1970	40626136
1971	41949040
1972	41283416
1973	39807920
1974	40867552
1975	39850864
1976	39487688
1977	38724776
1978	40627208
1979	41114184
1980	40383484
1981	39390828
1982	38271524
1983	37701092
1984	37145840
1985	37567696
1986	37029336
1987	38491944
1988	37296936
1989	35524556
1990	37099828
1991	36695752
1992	36776680
1993	36054672
1994	34912172
1995	35627768
1996	34613784
1997	34980816
1998	34983776
1999	33526792
2000	30893420
2001	29441200
2002	28384840
2003	22534806
2004	20222980
2005	18005274
2006	16700533
2007	13628625
2008	12418687
2009	12192675
2010	11400000
2011	10900000
2012	10800000
2013	10000000
2014	10100000
2015	10700000
2016	10600000
2017	10400000
2018	10600000