Year	Number
1976	7.87059
1980	7.50538
1981	3.87162
1982	6.18689
1983	5.68947
1984	6.41755
1985	5.86512
1986	5.42127
1989	7.96632
1990	8.92821
1999	20.76333
2000	19.45538
2008	29.05828
2009	30.66765
2011	34.60677