Year	Number
1977	8.099670270357839
1978	6.513056234871383
1979	7.686889209292239
1980	12.759570609208557
1981	6.6410627032096965
1982	7.137662652931441
1983	6.20808029847214
1984	4.805432467684401
1985	10.531477213295226
1986	14.563640397182875
1987	12.755136739980157
1988	8.879615710536457
1989	8.274341105948363
1990	9.172221746309681
1991	7.441706084503073
1992	9.626478262524964
1993	6.9180083532154955
1994	9.087942375435386
1995	11.932131132897196
1996	10.460776286550557
1997	10.326896304461759
1998	17.537888084740665
1999	18.723625225813993
2000	26.67720946669741
2001	25.926956464963183
2002	18.232051991954
2003	25.95617746675934
2004	27.539693934946204
2005	32.13090576338978
2006	40.23842392847772
2007	43.772086284493554
2008	38.679424629713
2009	43.00930264919999
2010	38.55771545938537
2011	79.23721827249241
2012	40.52513702657383
2013	31.692093307162303
2014	28.693877908734045
2015	43.247784057414975
2016	69.98324182445364
2017	58.57891634874042
2018	50.62352236154289
2019	38.05661029897328
2020	65.15285876361983
2021	36.814258722475856