Year	Percent
1990	2.4
1991	2.41
1992	2.43
1993	2.45
1994	2.47
1995	2.48
1996	2.49
1997	2.49
1998	2.5
1999	2.5
2000	2.51
2001	2.52
2002	2.52
2003	2.53
2004	2.53
2005	2.53
2006	2.53
2007	2.52
2008	2.4
2009	2.65
2010	2.6
2011	2.51
2012	2.4
2013	2.35
2014	2.3
2015	2.26
2016	2.26
2017	2.17
2018	2.11
2019	2.03