Year	Number
1991	63.4210526316
1992	68.4600977248
1993	67.8995874178
1994	67.4341050164
1995	66.928297903
1996	65.4675927632
1997	64.9434523575
1998	62.7833549479
1999	62.1855864172
2000	61.5231338816
2001	60.1688778646
2002	58.632735339
2003	57.0965928134
2004	55.5604502878
2005	51.7766854258
2006	47.9929205638
2007	44.2160087719
2008	44.5454130117
2009	44.8816703216
2010	45.2165570175
2011	41.7160087719
2012	38.2136330409
2013	34.7121710526
2014	34.308753655
2015	33.9053362573
2016	33.5019188596
2017	33.5019188596
2018	33.5019188596
2019	33.5019188596
2020	33.5019188596