Year	%
1988	19.42
1989	24.26
1990	14.91
1991	22.11
1992	26.91
1993	23.69
1994	24.09
1995	13.7
1996	13.22
1997	12.07
1998	11.05
1999	14.22
2000	10.26
2001	10.54
2002	6.58
2003	6.67
2004	5.93
2005	5.16
2006	4.82
2007	5.41
2008	4.9
2009	4.29
2010	5.22
2011	6.33
2012	4.89
2013	5.18
2014	5.54
2015	5.78
2016	4.57
2017	5.15