Year	%
1991	14.45
1995	12.51
1996	14.51
1997	14.67
1998	14.65
1999	16.06
2000	17.89
2001	18.02
2002	15.47
2003	18.27
2004	10.29
2005	9.27
2006	8.13
2007	6.31
2008	6.11
2009	5.11
2010	7.41
2011	7.03
2012	6.32
2013	6.06
2014	2.82
2015	5.72
2016	5.8
2017	2.8
2018	3.14