Year	Number
1971	22009
1972	26130
1973	30495
1974	34731
1975	40229
1976	52207
1977	60742
1978	67058
1979	72627
1980	80470
1981	88617
1982	103937
1983	115211
1984	126726
1985	137700
1986	152125
1987	165463
1988	180270
1989	197869
1990	215532
1991	228980
1992	231674
1993	238469
1994	251182
1995	262628
1996	260919
1997	259509
1998	262653
1999	270486
2000	273144
2001	280248
2002	285744
2003	248370
2004	254602
2005	262807
2006	272331
2007	284034
2009	304250
2010	326588
2011	334956
2012	364017
2013	376649
2014	409776
2015	460975
2016	467723
2017	486086
2019	553678
2020	462333