Year	Percent
1991	5.3567
1992	5.054
1993	5.1167
1994	4.90149
1995	4.77491
1996	4.8437
1997	4.91001
1998	4.8492
1999	4.9331
2000	4.85739
2001	4.7543
2002	4.38211
2003	3.91311
2004	3.7379
2005	3.58
2006	3.4119
2007	3.3206
2008	3.3073
2009	3.23429
2010	3.2304
2011	2.8199
2012	2.8018
2013	2.6182
2014	2.8005
2015	2.6388
2016	2.62
2017	2.59601
2018	2.61691
2019	2.55613