Year	Percent
1991	30.115
1992	31.502
1993	32.841
1994	32.432
1995	34.465
1996	33.311
1997	32.089
1998	33.089
1999	33.641
2000	33.563
2001	33.097
2002	31.441
2003	29.734
2004	30.736
2005	30.303
2006	29.798
2007	26.59
2008	28.459
2009	26.503
2010	24.376
2011	25.905
2012	26.06
2013	24.021
2014	23.946
2015	22.84
2016	19.005
2017	18.96
2018	18.848
2019	18.694
2020	18.404
2021	17.909
2022	17.401