Year	Number
1975	4.865672492566108
1976	3.9797686632003972
1977	4.835135312369927
1978	7.153199820211072
1979	8.105843891147046
1980	5.979258672015211
1981	4.86040611781603
1982	4.235952618860207
1983	4.253351339926192
1984	5.508259557578317
1985	5.209860033677697
1986	5.662656481932098
1987	7.25202314460978
1988	6.819092957653929
1989	6.535111337962278
1990	6.120662517145266
1991	6.962943195611862
1992	4.440841524326152
1993	5.079518073298939
1994	4.594675875237405
1995	3.145828023520048
1996	4.564268196044761
1997	5.163462917422724
1998	3.925656318834107
1999	2.2145132785348927
2000	1.9758343826245839
2001	1.8402406291071811
2002	2.0346970401846334
2003	1.0935467799567764
2004	0.6525761944146543
2005	0.5073995775778406
2006	0.4835941771306366
2007	0.38489437055437237
2008	0.38628962558709845
2009	0.7351342119011068
2010	0.8042539791321696
2011	1.0501370340877156
2012	1.3084906657789204
2013	1.1719042593345512
2014	1.2319338538756512
2015	1.5173987794007422
2016	1.7625851910835553
2017	1.7292599483139939
2018	1.5816604282663733
2019	1.7278749764658596
2020	2.2618496315412275
2021	2.0329781277781795
2022	1.7641254939316886
2023	1.8601445610463805