Year	Percent
1991	28.03
1992	27.608
1993	27.446
1994	27.073
1995	38.045
1996	37.701
1997	36.973
1998	38.263
1999	37.887
2000	37.673
2001	37.328
2002	37.21
2003	36.605
2004	36.247
2005	36.117
2006	36.695
2007	36.446
2008	32.753
2009	33.119
2010	33.361
2011	31.256
2012	31.274
2013	31.079
2014	30.762
2015	30.555
2016	30.264
2017	29.932
2018	29.898
2019	29.858
2020	29.814
2021	29.764
2022	29.713