Year	Percent
1989	46.59686
1990	45.00357
1991	45.86486
1992	42.25027
1993	40.52551
1994	41.21529
1995	34.53973
1996	35.34715
1997	34.68943
1998	33.94433
1999	33.49643
2000	33.91919
2001	31.83729
2002	28.98238
2003	28.65313
2004	31.70222
2005	32.62923
2006	31.78026
2007	31.22205
2008	30.78692
2009	29.32695
2010	29.99961
2011	29.25855
2012	29.25629
2013	28.20521
2014	27.9042
2015	29.77502
2016	29.28195
2017	30.04674