Year	Percent
1990	3.04
1991	2.62
1992	2.67
1993	2.62
1994	2.5
1995	2.51
1996	2.66
1997	2.72
1998	2.61
1999	2.6
2000	2.53
2001	2.73
2002	2.81
2003	2.72
2004	2.85
2005	3.36
2006	3.42
2007	3.68
2008	3.92
2009	4.04
2010	4
2011	4.59
2012	4.94
2013	5.4
2014	5.77
2015	6.06
2016	6.59
2017	7
2018	7.41
2019	7.8