Year	Percent
1990	11.96
1991	12.5
1992	12.35
1993	12.12
1994	11.8
1995	11.4
1996	11.09
1997	10.8
1998	10.38
1999	8.65
2000	7.87
2001	7.3
2002	6.48
2003	5.64
2004	5.33
2005	5.68
2006	5.13
2007	4.87
2008	4.8
2009	4.68
2010	4.77
2011	4.86
2012	4.76
2013	4.7
2014	4.82
2015	4.73
2016	4.93
2017	5.52
2018	5.43
2019	5.5