Year	Number
1971	63.6922
1972	65.94065
1973	65.42896
1974	65.01622
1975	68.3403
1976	66.51607
1977	66.89929
1978	64.6626
1979	61.83406
1980	60.70299
1981	59.6063
1982	60.58007
1983	62.1258
1984	68.28585
1986	65.6329
1987	60.33869
1988	62.77055
1989	70.38736
1990	90.38285
1991	77.02522
2005	88.62691
2008	100.23649
2009	94.61257
2010	84.32027
2011	81.31051
2012	80.11576
2016	83.41195