Year	Number
1960	1.2116295300414475
1961	1.0269327346688921
1962	1.0143950916349411
1963	0.6382026718432686
1964	0.607753531146776
1965	0.5470949222908575
1966	0.6293517337951634
1967	0.7058570148361811
1968	0.9084715409172311
1969	1.0853453671069535
1970	1.0433748831318572
1971	0.5466320589846168
1972	0.47081770475221507
1973	0.4487912209694486
1974	0.18697862558577683
1975	0.21395423987150233
1976	0.3070866969892086
1977	0.42498218238256097
1978	0.8440311000352788
1979	0.9084475898183546
1980	0.8908687750038683
1981	0.8941935255503796
1982	1.140958340472264
1983	1.366311729771706
1984	1.5763180890714155
1985	1.531201263306863
1986	2.154975830798582
1987	1.7919673945799734
1988	2.116952779500417
1989	2.5774098593464965
1990	3.7292928113490484
1991	4.316606847843653
1992	7.84606717901351
1993	6.566261701456238
1994	6.824920235733104
1995	6.199173581023518
1996	4.316737641126767
1997	4.487734782945023
1998	4.843880074776105
1999	4.38783694659136
2000	4.030593639403482
2001	4.680237183267272
2002	4.584927033696267
2003	4.497507379762376
2004	4.415706502693538
2005	0.9317453668149809
2006	0.7716346423601932
2007	0.6858135293562087
2008	0.5540730416368551
2009	0.6581528230397089
2010	0.6344313275251066
2011	0.5929953416505863
2012	0.5706455458348123
2013	0.5646234247874478
2014	0.625745236943273
2015	0.7645445710927473
2016	0.8807170532419292
2017	0.9475069729292956