Year	Percent
1989	18.5829
1990	18.68046
1991	20.62549
1992	23.25752
1993	29.65029
1994	28.65609
1995	36.6617
1996	41.31429
1997	35.49307
1998	33.80531
1999	21.38002
2000	13.05792
2001	14.42999
2002	21.25972
2003	15.05546
2004	13.48644
2005	11.3667
2006	10.4374
2007	12.9848
2008	13.66807
2009	17.55651
2010	23.69181
2011	26.0224
2012	32.88241
2013	39.59097
2014	27.44235
2015	35.24581
2016	34.62026
2017	34.80476