Year	Percent
1989	32.0751
1990	27.64315
1991	26.11542
1992	23.98092
1993	25.87794
1994	35.38885
1995	47.07325
1996	45.65193
1997	40.59123
1998	41.88785
1999	53.70379
2000	62.44488
2001	55.4606
2002	55.08702
2003	57.75106
2004	61.21126
2005	51.4783
2006	46.6242
2007	44.84405
2008	46.92328
2009	46.37503
2010	47.0534
2011	49.81634
2012	35.41546
2013	42.95672
2014	48.59296
2015	52.59768
2016	49.28809
2017	47.94731