Year	Percent
1991	0.05
1992	0.4
1993	1.11
1994	7.54
1995	10.98
1996	12.96
1997	13.01
1998	13.13
1999	13.46
2000	12.75
2001	10.43
2002	9.33
2003	8.78
2004	8.4
2005	8.13
2006	7.79
2007	7.26
2008	6.63
2009	6.55
2010	5.77
2011	5.39
2012	5.29
2013	5.2
2014	5.06
2015	4.93
2016	4.96
2017	4.9
2018	4.85
2019	4.8
2020	4.89