Year	Percent
1991	27.86
1992	27.213
1993	26.472
1994	25.706
1995	26.917
1996	24.056
1997	22.288
1998	20.15
1999	19.491
2000	19.334
2001	16.862
2002	16.044
2003	14.918
2004	17.08
2005	18.34
2006	19.171
2007	19.665
2008	20.112
2009	17.348
2010	15.262
2011	15.076
2012	14.794
2013	14.663
2014	14.465
2015	15.801
2016	14.939
2017	14.589
2018	14.373
2019	14.048
2020	14.006
2021	13.924
2022	13.819