Year	Number
1976	4.505591100327721
1977	6.2752941376176405
1978	4.933073212054904
1979	5.4011478630985765
1980	3.5188884504628346
1981	3.065403208639337
1982	3.7358030693177464
1983	3.7406459420317724
1984	3.5935327433159627
1985	4.194314789246299
1986	3.7024739537103746
1987	3.248099970434389
1988	2.345170239553839
1989	2.4392569772280877
1990	2.9833063607742516
1991	1.827492482918347
1992	1.2797297198312527
1993	0.8518185871165683
1994	0.6121734693437137
1995	1.3250365277968055
1996	2.6465418390342235
1997	1.6613632016529734
1998	1.1767294965647332
1999	1.2825818116275285
2000	1.8130074701413619
2001	2.8628093878714296
2002	1.9947391034636544
2003	2.451352866760917
2004	2.7197221788918813
2005	2.7652201792475912
2006	3.9773910465191915
2007	4.784568065265919
2008	4.287116785955703
2009	5.845044829156733
2010	5.4046083497614275
2011	6.679844343498935
2012	5.2220127895169135
2013	3.4198246211770456
2014	4.367588934445559
2015	3.3544490889227054
2016	4.152155944286712
2017	3.245391581594845
2018	3.6025614397204007
2019	3.384683932245867
2020	5.268924783525339
2021	5.17054662730014