Year	Percent
1991	26.85
1992	31.356
1993	32.152
1994	32.497
1995	32.938
1996	33.726
1997	35.804
1998	33.694
1999	33.336
2000	33.992
2001	34.976
2002	34.554
2003	34.825
2004	32.976
2005	32.607
2006	33.229
2007	31.548
2008	31.866
2009	30.817
2010	31.616
2011	32.277
2012	33.172
2013	33.299
2014	33.003
2015	32.513
2016	32.046
2017	32.055
2018	32.003
2019	31.92
2020	31.838
2021	31.72
2022	31.65