Year	Percent
1981	100.27453
1982	99.3237
1983	99.57287
1984	102.30143
1985	103.41217
1986	103.39555
1987	101.96204
1988	104.17818
1989	99.93844
1990	99.1862
1993	100.77144
1994	101.5476
2004	102.40486
2006	96.38511
2007	98.14437
2008	100.14427
2009	102.46861
2010	102.65598
2011	102.37876
2012	101.89225
2013	99.69868
2014	97.78098
2015	99.33085
2016	97.59047