Year	Number
1971	25052
1972	23659
1973	23095
1974	20205
1975	19777
1976	20758
1977	24700
1978	22560
1979	24145
1989	31917
1990	32935
1991	34972
1992	37872
1993	40665
1999	46893
2000	47262
2001	45663
2002	44368
2003	41917
2004	39872
2005	37401
2006	34739
2007	32932
2008	30487
2009	27483
2010	25326
2011	23785
2012	22646
2013	22231
2014	22862
2015	24252
2016	26436
2017	28438
2018	30169
2019	32530
2020	33961
2021	35450
2022	36791