Year	Percent
1991	39.178
1992	38.463
1993	38.802
1994	38.868
1995	38.045
1996	37.154
1997	36.183
1998	37.263
1999	38.499
2000	38.852
2001	38.867
2002	42.796
2003	39.794
2004	38.818
2005	38.657
2006	37.12
2007	33.271
2008	31.053
2009	32.552
2010	30.209
2011	29.336
2012	28.753
2013	27.455
2014	25.884
2015	23.443
2016	25.552
2017	25.525
2018	25.188
2019	24.771
2020	24.363
2021	23.986
2022	23.601