Year	%
1988	5.27
1989	6.62
1990	8.37
1991	10.3
1992	8.92
1993	7.42
1994	8.87
1995	7.2
1996	6.75
1997	6.26
1998	6.03
1999	6.67
2000	6.47
2001	6.44
2002	5.69
2003	5.24
2004	5.08
2005	4.68
2006	4.85
2007	4.58
2008	4.39
2009	4.42
2010	4.81
2011	4.85
2012	4.45
2013	4.51
2014	4.02
2015	4.1
2016	4.53
2017	3.85