Year	Percent
1991	30.172
1992	30.042
1993	27.817
1994	20.015
1995	30.838
1996	29.374
1997	32.213
1998	31.533
1999	34.412
2000	35.068
2001	34.77
2002	35.296
2003	33.776
2004	37.443
2005	37.855
2006	37.233
2007	35.342
2008	36.692
2009	33.718
2010	37.387
2011	36.781
2012	34.719
2013	37.335
2014	36.033
2015	36.225
2016	37.535
2017	37.422
2018	37.346
2019	37.387
2020	37.399
2021	37.442
2022	37.455