Year	Percent
1991	3.84173
1992	3.77068
1993	3.71365
1994	3.60917
1995	3.49228
1996	3.25075
1997	3.24472
1998	3.04908
1999	2.98848
2000	2.9072
2001	2.64463
2002	2.52188
2003	2.54701
2004	2.48504
2005	2.32072
2006	2.22606
2007	2.25122
2008	2.12105
2009	2.17707
2010	2.10049
2011	1.98944
2012	2.05926
2013	2.03263
2014	1.97489
2015	2.03676
2016	1.88543
2017	1.83092
2018	1.73344
2019	1.69164