Year	Percent
1991	4.69137
1992	4.71
1993	3.61699
1994	4.66636
1995	5.04965
1996	5.42161
1997	3.13218
1998	2.20196
1999	4.35902
2000	6.90512
2001	5.21114
2002	5.26695
2003	5.66507
2004	6.91165
2005	5.54684
2006	7.66435
2007	8.00731
2008	8.14642
2009	8.32196
2010	7.87013
2011	8.64972
2012	8.56482
2013	7.98876
2014	7.07774
2015	7.13912