Year	Number
1977	3.762728071201041
1978	2.2624110245975144
1979	4.064933404226403
1980	4.994805184111196
1981	2.084830232331567
1982	2.141117279806905
1983	3.162450765910372
1984	2.2383655934055002
1985	2.448030046272048
1986	2.7762876653415773
1987	2.376347110213792
1988	1.961048876685831
1989	2.454396752137324
1990	3.7901758547864173
1991	3.3625259795025984
1992	1.7394223693255837
1993	1.8998440994235934
1994	2.5249384934238868
1995	2.5400466155350134
1996	7.02362432292462
1997	12.08015900850644
1998	13.437138936362839
1999	3.487315854462384
2000	6.0267453779878135
2001	5.361425573954417
2002	5.493549691749854
2003	5.745294721955742
2004	6.751282546492568
2005	7.407010138593432
2006	9.28094793318489
2007	8.110007818920865
2008	6.5325717480476015
2009	6.593316688826798
2010	4.63603716843698
2011	4.114073839303488
2012	4.851221690256217
2013	7.130989054545987
2014	7.295904022409705
2015	8.136751607946604
2016	9.384729749880355
2017	9.470192683096341
2018	7.115081583991541
2019	6.256007698638366
2020	8.897450873857773
2021	7.760239198445571
2022	6.603173954302907
2023	7.000997764364718