Year	Number
1978	10.50444
1980	12.84839
1981	12.55853
1982	12.86091
1984	14.975
1985	14.91647
1986	15.71059
1992	30.5844
2011	26.03305
2012	24.78482
2013	25.25274
2014	25.98509
2015	25.78369
2016	33.38521
2017	20.17303
2018	27.94423