Year	Number
1971	13863
1972	15632
1973	20123
1980	3009
1981	4798
1982	5206
1983	7060
1984	6866
1985	7147
1986	8745
1987	9774
1988	10662
1989	12194
1990	15899
1991	20624
1992	22888
1998	44334
1999	58196
2000	70260
2001	76540
2002	95096
2008	252481
2009	302868
2010	362805
2011	400265
2016	287600