Year	%
1991	12.98
1995	11.03
1996	15.38
1997	15.57
1998	15.43
1999	15.18
2000	18.76
2001	18.74
2002	13.66
2003	18.87
2004	9.49
2005	8.54
2006	7.21
2007	7.44
2008	7.59
2009	6.9
2010	10.61
2011	11.73
2012	11.51
2013	10.75
2014	4.95
2015	9.42
2016	9.41
2017	4.5
2018	4.52