Year	Percent
1991	43.01849
1992	41.15122
1993	44.15173
1994	46.57216
1995	45.06512
1996	42.84965
1997	41.57782
1998	45.70563
1999	48.93744
2000	50.88684
2001	51.04084
2002	49.65518
2003	43.00528
2004	40.49001
2005	40.65063
2006	33.60334
2007	32.76003
2008	31.05693
2009	28.17
2010	27.52143
2011	27.52681
2012	26.45095
2013	28.81016
2014	30.47756
2015	34.15077
2016	33.69651
2017	32.3384
2018	24.55468
2019	21.0398