Year	Percent
1991	4.2988
1992	2.17546
1993	3.17631
1994	6.6363
1995	2.77322
1996	4.66032
1997	15.01493
1998	9.59946
1999	5.39411
2000	4.47763
2001	4.8243
2002	7.45686
2003	5.50013
2004	5.23043
2005	6.17437
2006	8.17913
2007	6.11967
2008	5.39644
2009	7.08528
2010	10.24604
2011	11.76861
2012	14.21261
2013	14.31574
2014	17.83938
2015	27.91422
2016	15.23536