Year	Percent
1990	2
1991	1.6
1992	2.58
1993	3.25
1994	3.53
1995	3.02
1996	3.62
1997	4.09
1998	3.32
1999	2.67
2000	2.25
2001	2.06
2002	2.65
2003	3.66
2004	3.98
2005	3.85
2006	3.53
2007	3.15
2008	2.87
2009	3.67
2010	4.54
2011	4.06
2012	4.12
2013	4.46
2014	4.63
2015	4.37
2016	4.72
2017	4.65
2018	4.53
2019	4.07
2020	4.6