Year	%
1990	28.07
1992	28.46
1993	44.42
1995	27.19
1996	26.57
1997	22.4
1998	25.03
1999	21.07
2000	25.23
2001	20.64
2002	25.18
2003	22.23
2004	16.74
2005	14.53
2006	13.67
2007	13.09
2008	15.33
2009	12.6
2010	14.15
2011	13.82
2012	9.88
2013	9
2014	7.42
2015	7.15
2016	7.52
2017	7.36