Year	Number
1970	2.9968233051203317
1971	2.777538009609142
1972	3.078538403705667
1973	3.8270230471987547
1974	4.502913952803839
1975	3.585498778774137
1976	3.0263529045409108
1977	3.0808500004479664
1978	3.3996583647662053
1979	5.745639850256293
1980	5.824547712112405
1981	3.8478479609600544
1982	4.58689118325688
1983	3.7035443611045573
1984	2.5221355219779915
1985	2.783066209932414
1986	3.0148707200695615
1987	3.0995523002967076
1988	2.481403047859492
1989	2.653237576505962
1990	2.592186831357701
1991	2.458362798058544
1992	2.1879993389880052
1993	2.2727726085446687
1994	1.9624400482454967
1995	1.8579328498610335
1996	1.5882188018265653
1997	1.2008762864923734
1998	1.2521580770317087
1999	1.082920809791027
2000	0.9161774129192478
2001	1.0176286235963228
2002	1.1774765140994852
2003	1.2123722607952547
2004	1.0574185268760292
2005	0.9006352338515805
2006	0.9089485796150776
2007	1.0418425196330166
2008	1.0533749293671268
2009	1.8539473803400062
2010	1.9164151173650323
2011	1.8773024007960206
2012	1.9557965725453121
2013	1.5473522287486519
2014	1.4535098175075316
2015	1.3832510777179805
2016	1.4763093100665945
2017	1.50213238501553
2018	1.372092037174798
2019	1.5364055209476972
2020	2.057686054410271
2021	1.9490545375057646
2022	1.6557491754656863
2023	1.7850311196601334