Year	Percent
1991	36.042
1992	35.742
1993	34.818
1994	34.405
1995	32.754
1996	32.702
1997	32.656
1998	31.615
1999	31.332
2000	30.867
2001	31.598
2002	31.271
2003	31.455
2004	32.571
2005	33.707
2006	31.831
2007	32.385
2008	33.45
2009	31.784
2010	29.673
2011	31.312
2012	30.032
2013	26.166
2014	24.778
2015	24.86
2016	26.174
2017	26.258
2018	26.122
2019	26.035
2020	25.957
2021	25.907
2022	25.828