Year	Number
1972	21072
1973	23284
1974	24810
1975	25524
1976	26442
1977	25872
1978	27775
1979	28636
1980	30152
1981	12747
1982	16316
1983	14074
1984	14144
1985	18612
1986	24996
1987	24411
1988	23961
1989	23107
1990	19384
1991	19902
1992	19224
1993	17709
1994	16511
2001	22262
2002	23083
2005	24307
2006	26424
2007	24523
2008	25583
2009	25324
2010	27607
2011	28279
2012	29505
2013	30780
2014	31080
2015	32284
2018	32996