Year	Percent
1971	63.54115
1987	90.07358
1988	89.06933
1989	89.14148
1990	91.16125
1991	94.40933
1992	97.02058
1993	101.66974
1994	98.29444
1995	101.49505
1997	99.09473
2000	93.78996
2001	97.48244
2002	97.69943
2003	95.83798
2004	100.40686
2005	101.04229
2006	99.42997
2007	94.87248
2008	97.44655
2009	101.76019
2010	103.73171
2011	103.41802
2012	101.49337
2015	101.26366