Year	Number
1976	8.940496507550039
1977	8.590767344305087
1978	9.791998469327464
1979	8.727148024839297
1980	6.862484727200971
1981	7.218212425897457
1982	8.117406409037121
1983	8.877220667152088
1984	7.777882198045187
1985	7.788186780837874
1986	8.126541382286176
1987	7.749028650451138
1988	6.447424985589359
1989	5.597972560380988
1990	4.845181645642805
1991	4.51768324053648
1992	3.7124023858457575
1993	4.11408652493154
1994	4.607446879061397
1995	3.364666717232926
1996	3.4447161954025045
1997	3.161935487627843
1998	3.2412041639528395
1999	3.3331298055264593
2000	2.925153139692834
2001	3.495104876236229
2002	4.4531319675272645
2003	4.568455108181593
2004	3.798452777982843
2005	3.191261903109795
2006	3.6398817011833446
2007	3.3465609312511337
2008	2.7730514747894035
2009	4.288542817381847
2010	4.589200986338291
2011	5.463832017346088
2012	3.8439061784438104
2013	3.790033159901539
2014	4.042598247429115
2015	4.72664663494373
2016	5.948654823579279
2017	5.095452546670821
2018	4.630768997026809
2019	5.228093645762104
2020	6.467636486994539
2021	5.327513209073849
2022	3.703160988303993
2023	3.937991504969424