Year	Number
1971	45.46252
1972	42.84154
1975	26.72873
1976	24.50309
1977	22.53211
1980	26.14286
1981	26.05393
1982	28.39878
1983	21.00579
1984	19.53355
1985	21.0852
1986	18.5897
1994	21.08982
1995	22.34007
1999	14.0399
2002	16.83243
2004	16.77674
2006	15.38373
2007	15.33967
2008	15.78783
2009	12.99478
2010	14.1453
2011	18.20992
2012	20.98103
2013	17.48197
2014	18.1899
2015	21.04116
2016	19.02855
2018	19.44891