Year	%
1989	88.43
1990	53.53
1992	27.01
1993	27.73
1994	56.37
1995	44.94
1996	23.67
1997	20.81
1998	28.22
1999	26.17
2000	21.42
2001	23.18
2002	21.73
2003	19.58
2004	19.88
2005	14.13
2006	10.29
2007	11.65
2008	10.55
2009	7.51
2010	6.89
2011	7.72
2012	6.88
2013	7.05
2014	8.56
2015	7.83
2016	7.31
2017	5.93