Year	Percent
1991	0.11
1992	0.17
1993	0.52
1994	0.65
1995	0.8
1996	0.9
1997	1.03
1998	1.13
1999	16.25
2000	11.78
2001	10.91
2002	10.04
2003	9.17
2004	7.99
2005	7.26
2006	6.62
2007	6.33
2008	5.86
2009	5.74
2010	5.63
2011	5.42
2012	5.19
2013	4.97
2014	4.91
2015	4.96
2016	5
2017	5
2018	4.9
2019	4.85