Year	Percent
1992	2.09313
1993	2.31871
1994	2.50669
1995	2.53657
1996	2.82156
1997	2.83803
1998	3.29715
1999	3.63813
2000	3.43189
2001	3.0313
2002	3.0542
2003	2.99135
2004	3.33749
2005	3.04528
2006	2.84506
2007	2.41638
2008	2.14102
2009	2.47337
2010	3.4907
2011	5.17367
2012	7.83738
2013	9.49544
2014	9.48227
2015	8.96653
2016	8.40303
2017	7.67676