Year	Percent
1991	8.31377
1992	8.0072
1993	7.091
1994	6.89819
1995	6.5804
1996	6.13321
1997	5.8806
1998	5.76951
1999	5.4201
2000	5.2305
2001	5.2078
2002	4.92839
2003	4.7152
2004	4.13689
2005	4.1988
2006	4.2729
2007	3.9671
2008	3.6991
2009	3.6907
2010	3.7692
2011	3.6813
2012	3.6931
2013	3.6013
2014	3.6436
2015	3.7518
2016	3.8844
2017	3.7842
2018	3.7578
2019	3.88744