Year	Number
1970	11.90233
1971	9.46716
1972	10.10888
1973	9.9828
1974	10.39714
1975	15.61257
1976	13.68832
1977	13.77606
1978	15.14698
1979	10.90919
1980	10.24493
1981	10.39006
1982	10.14613
1983	11.20408
1994	13.56148
1995	12.15793
1996	13.77485
2007	12.92329
2008	13.10251
2009	13.84574
2010	14.11157
2011	13.74491
2012	13.54991
2016	14.2604
2017	13.34167