Year	Percent
1991	3.438
1992	4.253
1993	5.861
1994	6.545
1995	5.532
1996	4.3371
1997	4.2217
1998	7.6307
1999	5.7749
2000	4.1139
2001	5.4905
2002	3.9252
2003	8.7215
2004	7.3607
2005	9.083
2006	7.4652
2007	7.3924
2008	7.3949
2009	8.9912
2010	8.6804
2011	7.8952
2012	8.0043
2013	8.7767
2014	8.5618
2015	8.3961
2016	8.4036
2017	7.9782