Year	Percent
1991	16.29451
1992	15.55072
1993	23.15981
1994	15.36283
1995	27.12105
1996	25.96717
1997	25.75661
1998	29.9954
1999	32.71761
2000	34.24519
2001	35.78536
2002	40.60835
2003	51.83113
2004	47.97694
2005	44.63411
2006	44.7361
2007	37.4365
2008	42.68454
2009	41.00644
2010	56.2497
2011	50.3728
2012	50.50204
2013	52.82763
2014	53.50743
2015	52.32447
2016	55.9425
2017	53.9027