Year	Percent
1989	28.88063
1990	27.46365
1991	26.34919
1992	34.45234
1993	36.29251
1994	35.33145
1995	26.68321
1996	22.67079
1997	21.44594
1998	20.81721
1999	17.51295
2000	19.63015
2001	21.76404
2002	20.1488
2003	21.9702
2004	21.13424
2005	22.58479
2006	24.76142
2007	26.65363
2008	27.93959
2009	17.05982
2010	20.87338
2011	22.43692
2012	21.71551
2013	18.48863
2014	13.3965
2015	15.93332
2016	21.51871
2017	20.7486