Year	Number
1970	46.48234
1971	42.97594
1972	47.0079
1973	50.04371
1974	51.55862
1975	50.692
1976	50.29924
1977	47.18294
1978	44.15567
1979	43.92033
1980	53.55663
1981	55.27225
1983	51.40402
1984	46.95204
1985	46.97363
1986	47.83636
1987	48.07506
1988	57.8659
1989	60.39131
1990	63.00499
2005	47.03943
2006	47.53901
2007	44.75494
2008	43.72919
2009	45.75844
2010	42.97476
2017	30.05456
2018	30.05459