Year	Percent
1991	36.781
1992	37.014
1993	36.198
1994	35.99
1995	36.763
1996	35.51
1997	35.854
1998	36.339
1999	36.692
2000	35.63
2001	34.856
2002	33.223
2003	33.006
2004	33.817
2005	33.877
2006	33.547
2007	33.044
2008	32.645
2009	29.541
2010	29.059
2011	29.363
2012	28.931
2013	28.759
2014	28.156
2015	27.804
2016	26.979
2017	27.097
2018	26.959
2019	26.832
2020	26.72
2021	26.588
2022	26.486