Year	Percent
1987	31.27036
1988	31.08504
1989	35.46667
1990	24.19362
1991	15.37655
1992	19.91839
1993	11.66657
1994	9.01358
1995	18.3401
1996	25.19733
1997	21.68013
1998	15.44407
1999	18.02621
2000	20.00997
2001	17.99933
2002	17.60672
2003	11.82999
2004	14.48839
2005	16.41817
2006	24.19576
2007	26.643
2008	28.94896
2009	27.27036
2010	27.40159
2011	25.47296
2012	34.96107
2013	33.89884
2014	36.75673
2015	34.67147
2016	33.93918
2017	32.24492