Year	Percent
1988	9.93259
1989	10.6867
1990	10.65332
1991	11.25484
1992	11.6974
1993	11.98241
1994	13.02211
1995	16.01865
1996	17.0432
1997	18.54947
1998	19.79187
1999	19.2902
2000	19.35172
2001	18.63987
2002	15.50389
2003	16.84706
2004	16.85209
2005	14.025
2006	14.50622
2007	7.47995
2008	11.11546
2009	17.62325
2010	14.66321
2011	13.98003
2012	15.8457
2013	15.60532
2014	16.01279
2015	19.66319
2016	18.38106