Year	Percent
1988	11.75253
1989	12.37896
1990	11.99635
1991	13.09941
1992	12.66391
1993	13.42861
1994	13.63742
1995	13.71252
1996	13.76754
1997	14.64728
1998	15.1779
1999	16.4876
2000	18.62581
2001	18.31638
2002	17.45204
2003	16.90097
2004	17.81654
2005	17.4226
2006	17.1359
2007	13.99489
2008	13.30472
2009	15.25874
2010	15.25099
2011	14.96354
2012	15.97649
2013	16.08007
2014	16.00241
2015	16.66115
2016	16.90519