Year	Percent
1977	96.04627
1978	109.25869
1979	110.5203
1980	124.36673
1981	104.18521
1982	89.73812
1983	100.89806
1984	77.18353
1985	75.43322
1986	83.53766
1987	80.62526
1988	91.39494
1989	92.17408
1990	82.23779
1991	78.83153
1992	76.91022
1993	73.05994
1994	68.16603
1995	64.95438
1996	59.34797
1997	58.05454
1998	52.90454
1999	52.9297
2000	50.755
2001	53.64287
2002	47.17066
2003	56.44319
2004	56.13705
2005	57.82073
2006	60.49355
2007	55.72691
2008	63.93302
2009	54.34525
2010	63.46065
2011	59.60596
2012	57.49089
2013	53.3459
2014	50.76927
2015	45.50983
2016	46.4539
2017	45.26059