Year	Percent
1991	21.572
1992	26.088
1993	28.993
1994	32.513
1995	29.317
1996	28.611
1997	25.983
1998	24.75
1999	24.942
2000	23.949
2001	24.33
2002	24.161
2003	24.466
2004	24.145
2005	24.915
2006	23.007
2007	20.803
2008	20.895
2009	20.876
2010	21.858
2011	21.803
2012	19.767
2013	18.096
2014	15.632
2015	15.69
2016	13.929
2017	13.828
2018	13.782
2019	13.749
2020	13.716
2021	13.696
2022	13.683