Year	Percent
1990	9.99631
1991	9.33416
1992	8.48269
1993	8.03536
1994	7.86169
1995	7.29255
1996	7.28222
1997	7.12751
1998	7.01153
1999	6.72289
2000	6.50357
2001	6.02377
2002	5.89968
2003	5.94489
2004	5.82188
2005	5.67501
2006	5.81627
2007	5.66401
2008	5.56547
2009	5.42203
2010	5.29914
2011	5.2265
2012	5.09117
2013	4.99361
2014	4.86105
2015	4.77986
2016	4.69052
2017	4.45166
2018	4.35765
2019	4.31515
2020	4.35615