Year	%
1989	31.92
1990	18.95
1991	13.21
1992	13.64
1993	12.49
1994	12.24
1995	11.77
1996	12.88
1997	12.68
1998	13.07
1999	13.85
2000	13.32
2001	12.67
2002	12.62
2003	12.3
2004	11.38
2005	10.62
2006	10.26
2007	10
2008	9.42
2009	8.74
2010	7.8
2011	7.51
2012	7.52
2013	7.2
2014	7.17
2015	6.87
2016	6.94
2017	7.05