Year	%
1988	4.95
1989	4.31
1990	13.55
1991	9.87
1992	9.61
1993	9.45
1994	9.82
1995	10.4
1996	8.98
1997	7.61
1998	6.71
1999	6.52
2000	5.75
2001	6.4
2002	6.08
2003	5.38
2004	4.31
2005	5.62
2006	4.35
2007	5.14
2008	5.64
2009	5.33
2010	5.2
2011	5.45
2012	5.27
2013	5.54
2014	5.35
2015	4.52
2016	4.13
2017	4.31