Year	Number
1966	4.3304070731973185
1967	6.686394120949095
1968	4.584407216494846
1969	6.130713712910986
1970	5.322677925211098
1971	5.6083904521426176
1972	4.466758012941294
1973	3.8795374351885044
1974	3.6769310384143616
1975	4.326379853895355
1976	6.966667286859035
1977	5.784237131902019
1978	4.428048161678185
1979	5.070991496449621
1980	4.749281191429732
1981	4.259903616999385
1982	3.835521255073987
1983	4.224756839081757
1984	4.241129255669237
1985	4.387605864462169
1986	4.353168114326939
1987	5.34309565830678
1988	6.37520158191275
1989	8.07023058902221
1990	8.724218744707777
1991	11.66687454404718
1992	7.703241900074657
1993	7.381244495132823
1994	6.101301285358865
1995	5.710731288534492
1996	5.094317929242367
1997	5.913063235655036
1998	4.620368717251743
1999	5.999102186668742
2000	4.22361442914215
2001	3.8817007945921147
2002	4.624940513139796
2003	4.383243342016548
2004	6.232526901186766
2005	6.999942790440973
2006	6.995891931021238
2007	6.4098470385132575
2008	7.369682044975615
2009	6.283563205015114
2012	5.636662157689802
2013	7.212109155087711
2014	8.013711408879074
2015	9.712544061947517
2016	12.970691355775319
2017	21.321898881578008
2018	10.602889889238122
2019	7.548958348025069
2020	4.603580168217882
2021	3.9602194003700832
2022	4.592559875384388