Year	Percent
1991	31.275
1992	32.961
1993	32.497
1994	29.709
1995	31.59
1996	30.507
1997	29.205
1998	29.442
1999	31.608
2000	34.323
2001	34.758
2002	28.454
2003	34.756
2004	28.197
2005	29.522
2006	29.74
2007	31.389
2008	30.58
2009	30.823
2010	33.1
2011	35.546
2012	37.143
2013	33.47
2014	35.592
2015	37.314
2016	35.214
2017	36.263
2018	36.743
2019	37.072
2020	37.174
2021	37.108
2022	36.854