Year	Percent
1991	36.196
1992	39.833
1993	39.41
1994	41.964
1995	36.709
1996	36.492
1997	36.664
1998	37.005
1999	37.07
2000	36.581
2001	36.321
2002	35.546
2003	34.939
2004	34.926
2005	34.301
2006	33.457
2007	32.513
2008	31.304
2009	31.128
2010	32.091
2011	31.179
2012	30.256
2013	29.568
2014	28.708
2015	28.243
2016	27.172
2017	26.874
2018	26.243
2019	25.712
2020	25.142
2021	24.572
2022	24.001