Year	Percent
1993	14.16
1994	15.55
1995	17.86
1996	18.63
1997	20.35
1998	21.33
1999	20.33
2001	15.37
2002	15.31
2005	17.06
2006	15.09
2007	13.01
2012	22.12
2014	19.91
2015	15.06
2016	13.62
2017	15.63