Year	Percent
1990	2.15
1991	2.16
1992	2.17
1993	2.19
1994	2.17
1995	2.49
1996	2.94
1997	3.26
1998	3.43
1999	1.94
2000	2.57
2001	4.62
2002	4.92
2003	4.86
2004	4.45
2005	5.5
2006	5.1
2007	5.38
2008	6.31
2009	6.77
2010	6.85
2011	7.55
2012	8.09
2013	7.76
2014	8.18
2015	8.15
2016	8.59
2017	8.21
2018	8.29
2019	8.69