Year	Number
1971	61.85249
1972	64.19569
1973	63.43105
1974	63.04043
1975	60.79438
1976	58.72304
1978	51.79566
1979	52.51186
1980	55.89872
1981	54.36627
1982	58.1442
1983	57.69873
1984	56.79136
1985	60.70168
1986	61.43383
1987	63.77437
1988	66.09692
1989	62.99504
1990	64.42506
1991	65.17788
1992	63.20272
1993	69.05732
1994	73.41823
1995	82.16833
1996	72.74795
1997	72.91752
1998	63.95559
1999	61.22946
2000	60.48057
2001	59.49181
2002	56.20777
2003	65.17102
2004	82.79541
2006	54.79663
2007	58.48011
2008	51.80477
2009	64.38062
2010	49.14568
2011	47.09289
2012	44.442