Year	Number
1971	44.38688
1972	42.84184
1973	40.89138
1974	32.32685
1982	31.45022
1983	36.82133
1984	31.77187
1985	29.81775
1986	31.273
1987	33.39832
1988	32.57673
1989	33.42115
1991	31.87673
1992	27.18103
1998	41.75324
2007	41.0124
2010	45.58651
2011	42.54306
2015	50.02951