Year	Percent
1991	7.78114
1992	7.61962
1993	7.41407
1994	7.19927
1995	7.33562
1996	7.42831
1997	6.8924
1998	6.48501
1999	6.23291
2000	6.0508
2001	5.8048
2002	5.7587
2003	5.5038
2004	4.90171
2005	5.27381
2006	5.2445
2007	5.5268
2008	5.25221
2009	5.32228
2010	5.2133
2011	4.93751
2012	4.67521
2013	4.57569
2014	4.83691
2015	4.53099
2016	4.3482
2017	3.92981
2018	3.6941
2019	3.65594