Year	Percent
1991	38.01
1992	37.592
1993	35.749
1994	35.163
1995	35.525
1996	34.181
1997	32.846
1998	36.396
1999	34.44
2000	34.805
2001	32.171
2002	33.009
2003	32.169
2004	33.847
2005	30.345
2006	30.31
2007	29.911
2008	28.684
2009	27.683
2010	24.781
2011	20.225
2012	16.549
2013	14.996
2014	15.849
2015	15.13
2016	14.693
2017	15.893
2018	16.149
2019	16.715
2020	17.06
2021	17.219
2022	17.144