Year	Number
1970	44.79263
1971	44.97854
1972	42.59779
1973	42.87375
1974	39.91867
1975	39.74384
1976	40.65392
1977	40.81414
1978	44.19602
1979	41.96769
1980	39.65666
1981	40.74208
1982	46.28902
1983	37.76797
1984	35.35359
1986	36.53596
1991	32.15882
1993	29.22342
2000	19.48127
2004	19.59665
2005	21.26765
2006	25.74737
2007	26.89421
2008	29.38287
2009	26.5804
2013	14.34182
2015	20.70922
2016	19.34288