Year	Number
1975	4.259330994396064
1976	3.8326581874130072
1977	4.934697448764347
1978	5.802256942706928
1979	7.22248408496452
1980	6.48701227420945
1981	5.006919715576389
1982	5.757301408605122
1983	5.4064409430566505
1984	4.8784332086604785
1985	5.156827347656314
1986	4.867723897272468
1987	5.256490173456771
1988	4.215707927704016
1989	4.181654111544034
1990	3.816041466423337
1991	3.895353614173205
1992	3.337037788926579
1993	3.790366365816356
1994	3.7067133472722813
1995	3.3266851997518603
1996	3.41387710433369
1997	3.3334601063910667
1998	3.053507980159429
1999	2.9861407329249112
2000	2.6797141832886333
2001	2.664185756227642
2002	3.2605558885000976
2003	3.43876791723688
2004	3.718457981377149
2005	4.0749819699676095
2006	5.289547374072859
2007	6.545624156354747
2008	4.51627986050484
2009	6.5417308622901675
2010	6.162960747522543
2011	5.351817930225474
2012	6.646304120780247
2013	6.447138116531056
2014	5.938878735551534
2015	7.453844855813578
2016	8.063523632591558
2017	8.717877421821628
2018	8.004622907312568
2019	8.885966590037437
2020	11.711900494896167
2021	9.910479528208992
2022	8.146539132950835
2023	7.456238472332358