Year	Percent
1990	35.00298
1991	40.74539
1992	39.82076
1993	47.21898
1994	39.32804
1995	23.92792
1996	23.24
1997	20.27327
1998	19.00302
1999	20.75826
2000	23.37528
2001	25.46839
2002	29.35655
2003	32.15265
2004	29.73483
2005	28.80922
2006	23.35899
2007	19.18564
2008	15.0471
2009	15.47447
2010	20.83009
2011	23.75685
2012	27.56672
2013	28.35913
2014	28.56514
2015	29.728
2016	33.148
2017	38.05397