Year	Percent
1977	99.35902
1978	78.51675
1979	103.59373
1980	89.78092
1981	102.13624
1982	97.34178
1983	70.82304
1984	71.98634
1985	75.95759
1986	78.15724
1987	78.89082
1988	66.9781
1989	47.40257
1990	60.06933
1991	71.6204
1992	75.50856
1993	71.93938
1994	65.48704
1995	69.11715
1996	63.59169
1997	59.9456
1998	57.84075
1999	58.99251
2000	55.29063
2001	53.32566
2002	53.89047
2003	54.6278
2004	55.56217
2005	57.62131
2006	60.34384
2007	60.05854
2008	59.06016
2009	47.75786
2010	47.45854
2011	42.60742
2012	45.83958
2013	47.95221
2014	49.29499
2015	38.58929
2016	39.83398
2017	42.74348