Year	Percent
1987	3.95377
1988	7.10161
1989	7.28651
1990	7.91086
1991	5.59532
1992	3.37459
1993	2.25869
1994	2.64936
2003	2.12864
2004	2.01438
2005	1.78096
2006	1.93836
2007	2.30476
2008	2.15637
2009	2.26521
2010	2.30505
2011	1.9821
2012	2.15689
2013	2.17685
2014	2.28551
2015	2.36116
2016	2.44296
2017	2.28651