Year	Number
1970	50920
1971	56531
1972	65827
1973	74441
1974	79705
1975	89364
1976	99742
1977	109601
1978	120965
1979	128906
1980	130496
1981	129787
1982	129203
1983	129913
1984	133123
1985	134470
1986	135886
1987	137784
1988	139383
1989	139465
1990	144690
1999	128725
2000	134177
2001	142927
2002	147878
2004	151853
2005	157889
2006	209602
2007	217703
2008	223917
2009	230294
2010	238855
2011	239544
2016	291030
2017	268242