Year	%
1988	31.12
1989	49.25
1990	37.27
1992	34.72
1993	23.52
1994	28.29
1995	22.89
1996	12.43
1997	15.26
1998	17.68
1999	16.25
2000	14.94
2001	13.5
2002	16.23
2003	13.79
2004	12.58
2005	12.58
2006	12.17
2007	11.03
2008	10.8
2009	11.04
2010	10.16
2011	10.46
2012	10
2013	9.56
2014	10.79
2015	9.86
2016	9.8
2017	9.16