Year	Number
1975	3.8740548546305797
1976	7.312783222101535
1977	10.391042098320037
1978	10.560920797140179
1979	11.412896775781837
1980	8.258352404270356
1981	5.432987957638956
1982	5.431671898697516
1983	5.313544110418661
1984	5.38431568252224
1985	5.6031832062093505
1986	5.928524356197626
1987	5.781032456035212
1988	3.9904733157428725
1989	3.153607689239153
1990	2.0364027734551975
1991	2.9229663127463645
1992	3.371169861234037
1993	5.070948973562136
1994	6.880554226417403
1995	5.133859716794271
1996	5.009045892747253
1997	5.391801349486922
1998	5.674376853115306
1999	6.311481337102892
2000	6.1214797944892885
2001	7.452952436940927
2002	10.373083487159173
2003	12.283282014720765
2004	11.305109511999339
2005	8.518473171846145
2006	8.919928665118928
2007	11.139191931452583
2008	7.714252656941397
2009	9.773711143144505
2010	7.7606341102683905
2011	6.188790103476584
2012	5.903715095886608
2013	6.0277464953752355
2014	6.599133080201713
2015	8.003091829296523
2016	8.430139057682352
2017	8.162718669436286
2018	6.901055485123648
2019	8.273659400483963
2020	12.932328106578547
2021	9.842385744523282
2022	7.009512105443592
2023	7.97133516312324