Year	Percent
1971	0.98312
1972	0.98045
1973	0.98816
1974	0.98963
1975	0.99773
1976	0.99374
1977	1.0044
1978	0.9915
1979	0.99467
1980	1.00693
1981	0.87166
1982	0.97223
1983	0.9542
1984	0.95389
1986	0.99216
1987	0.99892
1988	1.01935
1999	1.0287
2000	1.03481
2001	1.03093
2002	1.02813
2003	1.02568
2004	1.02372
2005	1.02759
2006	1.02146
2007	1.01639
2008	1.0179
2010	1.02092
2011	1.02649
2012	1.02101
2013	1.01766
2014	1.01503
2015	1.02145