Year	%
1989	44.03
1990	32.17
1991	15.62
1992	13.58
1993	12.24
1994	11.06
1995	11.7
1996	12.93
1997	11.18
1998	10.71
1999	12.49
2000	11.44
2001	9.96
2002	9.74
2003	9.83
2004	9.74
2005	9.26
2006	9.19
2007	9.09
2008	9
2009	9.03
2010	9.13
2011	8.81
2012	8.99
2013	8.86
2014	8.73
2015	8.89
2016	9.52
2017	9.65