Year	Percent
1991	38.62
1992	35.842
1993	34.624
1994	31.973
1995	31.318
1996	30.264
1997	30.139
1998	30.485
1999	30.293
2000	30.263
2001	30.405
2002	30.319
2003	29.771
2004	32.845
2005	30.518
2006	30.411
2007	29.62
2008	29.319
2009	26.141
2010	24.085
2011	22.683
2012	21.585
2013	18.42
2014	17.931
2015	18.426
2016	19.085
2017	19.919
2018	20.203
2019	20.11
2020	19.991
2021	19.838
2022	19.689