Year	Number
1971	35.5
1973	41.42105
1978	12.01866
1979	8.12216
1980	10.20579
1981	10.47305
1982	8.90617
1983	9.4751
1984	11.54343
1985	9.88766
1986	10.41899
1987	10.2301
1988	9.90714
1989	8.83037
1990	9.96604
1991	9.00775
1992	10.43664
1993	7.80134
1994	8.74257
1995	5.49284
1996	4.03804
1997	7.81435
1998	3.22959
1999	9.95545
2000	10.10673
2001	14.23338
2002	15.21966
2004	19.32768
2005	21.79439
2006	18.62466
2007	20.4851
2008	22.89388
2009	22.55518
2010	23.27195
2012	25.66397