Year	Number
1971	21.77413
1972	26.4728
1975	35.68449
1977	35.33997
1978	45.53502
1979	46.44857
1981	62.44613
1983	55.47896
1985	64.77592
1986	64.28742
1987	54.91874
1989	43.09886
1990	37.31739
2009	80.05232
2011	66.81707
2012	68.13149
2016	34.62948
2017	31.63737