Year	Percent
1987	3.84
1988	4.87
1989	3.7
1990	6.24
1991	4.92
1992	3.79
1993	4.23
1994	3.74
1995	4.96
1996	3.86
1997	4.1
1998	3.97
1999	4.22
2000	3.34
2001	3.55
2003	3.61
2004	3.53
2005	3.46
2006	3.2
2007	2.76
2008	2.62
2009	2.33
2010	2.86
2011	2.98
2012	3.31
2013	4.12
2014	3.7
2015	4.01
2016	3.63
2017	3.19