Year	Number
1979	8.405591803559933
1980	6.3720369002969655
1981	4.277189209173988
1982	4.561623752995623
1983	3.7963920540700666
1984	2.5471747945685737
1985	3.6232644125024245
1986	3.401089358241025
1987	4.369358882906227
1988	4.580163526045918
1989	5.085459113994413
1993	3.3575295623776364
1994	4.232511329601406
2005	12.744139464049113
2006	11.401901577780782
2007	9.5706214226187
2008	7.836093020266891
2009	9.092412285235879
2010	8.414795535806356
2011	5.269543501839032
2012	4.884903741198653
2013	4.796879843072569
2014	5.059128129170795
2015	4.9001774094344634
2016	6.076374179545734
2017	6.626855435413752
2018	6.230401786546892
2019	7.2664943872100975
2020	9.348568916640088
2021	4.325533931553517
2022	3.4857082609495587