Year	Percent
1988	10.28444
1989	11.06245
1990	11.95382
1991	10.60282
1992	10.53428
1993	8.80374
1994	9.37753
1995	21.74404
1996	20.1092
1997	19.91409
1998	20.85186
1999	21.89223
2000	22.49466
2001	21.41481
2002	21.85901
2003	24.0711
2004	24.1675
2005	23.21597
2006	24.01439
2007	24.78655
2008	24.68476
2009	24.95599
2010	24.28017
2011	23.37232
2012	24.34397
2013	24.02869
2014	24.05582
2015	24.83422
2016	26.06407