Year	Number
1971	4955
1972	4980
1973	3954
1974	4022
1975	4159
1976	4199
1977	4245
1978	4385
1979	4445
1980	4623
1981	4805
1982	5252
1983	5500
1984	5760
1985	6322
1986	6866
1987	7256
1988	7534
1989	8244
1990	9049
1991	9465
1992	9582
1993	10400
1996	9475
1998	11597
1999	12107
2000	12731
2001	14955
2002	16651
2003	17931
2004	18899
2005	21289
2006	24452
2007	28671
2009	33867
2010	36557
2011	40288
2012	42052
2013	44662
2014	46887
2015	47949
2016	42497
2017	42854
2018	51051
2019	51545
2020	51921
2022	42424