Year	Percent
1990	16.14869
1991	15.38803
1992	15.09025
1993	14.50911
1994	13.99429
1995	13.42463
1996	13.02897
1997	13.00126
1998	18.72937
1999	18.32212
2000	17.93591
2001	18.0045
2002	19.64247
2003	20.96698
2004	20.75113
2005	19.74664
2006	20.71002
2007	20.19406
2008	20.44993
2009	18.60352
2010	20.30323
2011	22.79385
2012	21.80158
2013	22.70315
2014	23.22699
2015	24.31805
2016	24.93266
2017	26.37039