Year	Percent
1993	18.7
1994	18.8
1995	19.1
1996	18.9
1997	18.28
1998	27
1999	24.8
2000	26.5
2001	21.34
2002	23
2003	21.3
2004	19.8
2005	18.2
2006	21.67
2007	21.68
2008	22.4
2009	22.25
2010	22.39
2011	23.31
2012	19.44
2013	20.53
2014	20.6
2017	17.66