Year	Percent
1991	39.401
1992	35.859
1993	38.296
1994	36.864
1995	39.206
1996	35.597
1997	35.28
1998	38.097
1999	37.85
2000	37.868
2001	39.553
2002	37.421
2003	33.662
2004	34.17
2005	34.607
2006	37.19
2007	35.748
2008	36.07
2009	30.955
2010	30.621
2011	30.315
2012	29.29
2013	26.207
2014	28.317
2015	29.575
2016	27.595
2017	27.955
2018	28.197
2019	28.862
2020	28.966
2021	28.596
2022	27.916