Year	Number
1977	2.5744342870333305
1978	1.0263471313582728
1979	0.7352669324843817
1980	0.44753593390099583
1981	0.598940001907165
1982	0.6943844604084505
1983	1.4605878182588918
1984	2.109298655664331
1985	2.791894927721992
1986	4.950987049673879
1987	6.11906505752117
1988	6.790588716290878
1989	7.493904931243805
1990	8.587895865520679
1991	7.100717492423073
1992	5.091108920246102
1993	4.677868129133061
1994	6.01034342217445
1995	5.535528708750923
1996	5.722032826653299
1997	5.338171181650956
1998	5.740782513948051
1999	5.740487971631762
2004	4.707751374753664
2005	3.0886750247696133
2006	2.770632736162081
2007	3.145604582613128
2008	2.609556407777854
2009	5.421415329303343
2010	4.945234699481652
2011	3.3140424620867135
2012	3.6377589459801083
2013	3.2794081658984116
2014	2.678932599769121
2015	3.4129909954748174
2016	2.4633778142390788
2017	3.389623837679417
2018	4.217627959221731
2019	4.2939034653034325
2020	8.179799877172872
2021	7.666391855824479
2022	7.064488944873293
2023	8.931405010465786