Year	Percent
1990	9.12
1991	12.35
1992	13.19
1993	11.99
1994	11.03
1995	9.75
1996	8.99
1997	9.98
1998	9.24
1999	8.31
2000	7.85
2001	7.32
2002	7.06
2003	6.76
2004	6.48
2005	6.22
2006	5.96
2007	5.71
2008	5.43
2009	4.59
2010	4.78
2011	10.73
2012	13.04
2013	10.14
2014	8.94
2015	8.59
2016	10.06
2017	12.18
2018	14.48
2019	15.59