Year	%
1988	16.41
1989	24.69
1990	14.11
1991	11.32
1992	25.32
1993	12.48
1994	17.54
1995	45.14
1996	12.59
1997	10.2
1998	16.52
1999	9.73
2000	9.74
2001	9.71
2002	10.26
2003	10.39
2004	6.99
2005	7.66
2006	7.39
2007	6.88
2008	7
2009	7.64
2010	7.85
2011	7.21
2012	6.98
2013	7.05
2014	7.16
2015	6.98
2016	7.05
2017	5.67