Year	Percent
1991	2.262
1992	3.8
1993	4.958
1994	5.136
1995	5.4515
1996	3.73
1997	3.6361
1998	2.4332
1999	1.64
2000	1.3226
2001	1.5552
2002	3.2871
2003	4.0221
2004	5.1481
2005	2.5965
2006	2.6356
2007	2.2362
2008	3.2485
2009	8.5611
2010	8.3101
2011	7.7681
2012	6.3069
2013	5.649
2014	4.9989
2015	3.9141
2016	2.9179
2017	2.7629