Year	Number
1965	2.4269778921602185
1966	3.146260386717835
1967	2.7473318373171596
1968	1.7872894846299998
1969	1.4968090867676398
1970	1.6539379437665698
1971	1.5987278621251977
1972	2.0261019089231036
1973	2.7513028112478604
1974	2.102370635175672
1975	1.500078315124796
1976	1.681997032115636
1977	1.7295282564148402
1978	2.115505368883132
1979	1.6822884788041288
1980	1.4298790833656794
1981	1.2615790101132642
1982	0.7347654373573885
1983	1.5380259195667136
1984	1.632317565143847
1985	1.4059352446039173
1986	1.5207637287053215
1987	2.109251810415309
1988	2.0406095806934523
1989	2.5212299739686803
1990	1.9150053028153433
1991	1.9454872136109762
1992	2.2079413294296413
1993	2.4848133422721053
1994	2.9202365244364494
1995	2.8772991016428477
1996	2.8890572882759473
1997	3.209312146006903
1998	4.452952437658879
1999	3.6840458628623938
2000	3.5730893438995426
2001	3.6314842582928675
2002	3.890342646773403
2003	3.994227309388967
2004	3.817273535148408
2005	4.55297796722898
2006	3.7068708826188517
2007	3.443454894605576
2008	4.417437232268604
2009	4.723776419317137
2010	3.9483621675618865
2011	4.531843594895543
2012	4.127555445306864
2013	4.406756381354409
2014	4.165000437105793
2015	7.531944244725398