Year	%
1988	5.88
1989	9.13
1990	6.82
1991	9.84
1992	11.28
1993	14.33
1994	12.27
1995	6.42
1996	6.92
1997	6.12
1998	5.72
1999	6.45
2000	5.6
2001	6.18
2002	4.85
2003	4.81
2004	4.33
2005	3.76
2006	3.4
2007	3.56
2008	3.51
2009	3.33
2010	3.39
2011	3.92
2012	2.61
2013	2.68
2014	3.1
2015	3.12
2016	3.01
2017	2.53