Year	Percent
1991	8.34925
1992	8.17259
1993	7.98343
1994	7.75512
1995	7.49179
1996	7.23409
1997	6.56006
1998	6.00982
1999	5.50613
2000	5.03726
2001	4.5671
2002	4.12667
2003	3.73554
2004	3.39243
2005	3.07198
2006	2.91051
2007	2.89125
2008	2.74207
2009	2.62897
2010	2.53624
2011	2.4368
2012	2.3459
2013	2.2648
2014	2.20665
2015	2.13435
2016	2.0617
2017	1.99807
2018	1.93285
2019	1.86961