Year	Number
1970	14.6087
1971	20.05882
1973	26.16667
1974	25.08696
1976	26.2439
1977	24.48077
1980	24.22449
1999	9.84217
2001	10.49398
2007	15.53846
2008	14.97176
2009	13.62469
2010	13.70316
2013	15.35443
2015	15.51085