Year	Number
1970	37.31655
1971	37.4494
1972	37.55867
1973	40.29404
1974	38.21274
1975	38.73574
1976	38.17236
1977	37.73788
1978	37.01582
1979	34.59854
1980	35.4533
1982	36.10351
1983	35.0092
1984	34.39661
1985	33.28301
1986	32.36723
1987	32.18421
1988	33.73767
1989	31.77275
1990	33.27105
1991	36.14958
1992	37.23898
1993	37.0349
1994	37.13624
1995	38.0089
1996	36.28506
1997	35.67281
1998	37.182
1999	34.3856
2000	35.66299
2001	36.71573
2002	35.20899
2003	34.47031
2004	35.01829
2005	33.55782
2006	33.2727
2007	30.55547
2008	29.19228
2010	30.21638