Year	%
1990	28.94
1992	28.97
1995	29.51
1998	29.27
2000	31.66
2002	33.91
2003	28.57
2004	28.28
2005	26.92
2006	26.85
2008	21.53
2009	20.94
2010	16.47
2011	15.99
2012	15.53
2013	14.06
2015	14.07
2016	11.56