Year	Percent
1991	2.33443
1992	2.27357
1993	2.19689
1994	2.12854
1995	2.07579
1996	2.12443
1997	2.19136
1998	2.27244
1999	2.34502
2000	2.40853
2001	2.47175
2002	2.53194
2003	2.58554
2004	2.6406
2005	2.70483
2006	2.64496
2007	2.58397
2008	2.50696
2009	2.4771
2010	2.42038
2011	2.35986
2012	2.2916
2013	2.22279
2014	2.15151
2015	2.08313
2016	2.00801
2017	1.93307
2018	1.85554
2019	1.77965