Year	Percent
1991	30.093
1992	29.225
1993	29.195
1994	29.472
1995	30.144
1996	29.131
1997	30.998
1998	32.229
1999	31.294
2000	32.474
2001	31.059
2002	30.567
2003	29.52
2004	29.818
2005	32.343
2006	35.094
2007	38.084
2008	41.132
2009	44.495
2010	44.401
2011	29.543
2012	28.195
2013	29.481
2014	30.403
2015	28.642
2016	29.126
2017	29.058
2018	28.973
2019	28.88
2020	28.816
2021	28.775
2022	28.719