Year	%
1988	5.98
1989	4.23
1990	12.77
1991	12.05
1992	11.71
1993	9.06
1994	11.69
1995	7.34
1996	9.77
1997	10.35
1998	9.64
1999	10.06
2000	8.74
2001	8.79
2002	8.45
2003	7.37
2004	7.39
2005	8.14
2006	7.7
2007	7.29
2008	7.08
2009	7.06
2010	6.42
2011	6.5
2012	7.06
2013	6.89
2014	7.3
2015	7.29
2016	6.77
2017	7.1