Year	Number
1971	50.88889
1972	42.85714
1982	45.6087
1983	51
1984	45.96552
1985	57.84
1986	55.4375
1987	44.79545
1989	48.59184
1999	28.05682
2000	27.5
2001	32.9697
2002	32.08108
2003	29.8705
2004	27.98113
2006	28.87173
2007	36.77449
2009	32.94283
2010	34.0773
2011	35.39198
2012	32.96333
2013	33.8499
2014	35.26698
2015	33.98462
2016	35.16858
2017	32.06993
2018	38.19347