Year	Number
1981	14.17378
1983	9.60087
1985	5.53974
1986	7.95032
1987	7.7089
1988	6.78465
1989	7.75776
1996	7.21682
1998	8.71654
2007	51.63464
2009	17.13728
2010	19.09827
2011	17.91528
2013	17.00124
2014	18.70033