Year	Percent
1991	32.947
1992	32.59
1993	32.562
1994	33.278
1995	32.95
1996	32.383
1997	32.202
1998	32.765
1999	33.75
2000	33.664
2001	32.738
2002	33.689
2003	33.292
2004	33.34
2005	33.51
2006	34.071
2007	34.288
2008	34.149
2009	40.382
2010	39.914
2011	41.008
2012	40.28
2013	40.896
2014	38.17
2015	38.192
2016	38.056
2017	37.972
2018	37.99
2019	38.019
2020	38.022
2021	38.024
2022	38.031