Year	%
1991	8.25
1995	8.63
1996	25.64
1997	17.09
1998	19.14
1999	20.57
2000	19.45
2001	20.77
2002	21.91
2003	21.52
2004	20.2
2005	17.57
2006	11.98
2007	17.44
2008	16.7
2009	13.58
2010	10.87
2011	9.93
2012	11
2013	9.95
2014	8.92
2015	8.06
2016	6.91
2017	5.46
2018	4.7