Year	Percent
1971	57.65778
1972	55.98426
1973	59.54398
1974	63.09684
1975	66.96621
1976	71.33801
1977	72.88777
1978	71.6607
1979	76.51248
1980	79.5077
1987	95.81006
1988	95.27749
1994	94.85287
1995	92.57365
1996	92.14266
1997	95.4147
1999	95.93499
2000	96.43605
2001	96.46472
2002	96.64808
2003	96.00022
2004	95.85254
2005	100.15301
2006	100.46703
2007	100.00463
2010	98.72373
2011	105.61479
2012	109.79228
2013	111.14925
2014	111.70112
2015	115.08029
2016	108.38575
2017	104.4238