Year	Percent
1981	79.2638
1982	62.73224
1983	72.17391
1984	56.0559
1985	62.38372
1986	74.85014
1987	56.5272
1988	59.48995
1989	67.25722
1990	64.69281
1991	76.40566
1992	62.2667
1993	68.82968
1994	68.77165
1995	58.53121
1996	55.80968
1997	65.58814
1998	52.67078
1999	42.10459
2000	38.63246
2001	35.89059
2002	30.47958
2003	31.67568
2004	42.36715
2005	54.60583
2006	57.23535
2007	64.02444
2008	67.2
2009	57.6
2010	81.15693
2011	69.655
2012	61.17234
2013	62.68437
2014	61.21078
2015	53.31905