Year	Percent
1971	37.67977
1972	42.02654
1973	47.42168
1974	49.38288
1976	48.80338
1977	50.21575
1981	46.77769
1982	49.50325
1983	51.05708
1984	49.736
1987	63.02304
1988	66.88477
1989	64.70019
1991	67.38614
1992	69.08962
1993	71.71877
1995	73.9651
1996	77.86559
1998	81.74152
2000	89.30413
2001	89.83515
2002	88.7947
2003	88.23804
2005	89.97834
2006	89.56626
2007	95.03095
2008	96.25614
2009	99.0203
2010	99.68753
2011	103.743
2012	103.94586
2013	102.5179
2014	100.96937
2015	95.71307
2016	92.74601