Year	Percent
1971	48.83728
1972	56.55528
1973	55.70676
1974	57.81998
1975	54.64626
1976	102.28946
1977	88.1501
1978	64.40028
1979	54.64635
1980	59.94098
1981	47.31887
1982	20.32698
1983	24.17271
1984	25.60193
1985	34.825
1986	31.48664
1987	28.30576
1988	18.6483
1989	16.84876
1990	15.57225
1991	14.03394
1992	22.0629
1993	18.01247
1994	23.97638
1995	28.66553
1996	25.39496
1997	36.5783
1998	27.20826
1999	36.86723
2000	28.91385
2001	27.13359
2002	23.60826
2003	22.54974
2004	28.33554
2005	23.07638
2006	20.04894
2007	20.71824
2008	18.01063
2009	21.42241
2010	19.65458
2011	20.88298
2012	18.77741
2013	24.5823
2014	25.60509
2015	28.86782
2016	16.01724