Year	Percent
1974	32.60553
1975	40.5838
1976	44.55847
1977	52.38438
1978	55.53622
1979	61.74281
1980	66.32334
1981	69.93199
1982	76.72293
1983	77.38467
1984	76.31995
1985	71.49298
1986	75.90429
1987	77.06147
1988	74.39295
1989	80.22073
1990	87.64423
1991	94.04155
1992	93.44091
1993	91.7828
1994	91.28344
1995	89.23639
1996	85.48654
1997	87.54389
1998	85.63764
1999	85.06304
2000	81.57958
2001	78.14829
2002	79.25969
2007	97.95421
2009	86.38228
2010	87.40411
2011	87.89884
2012	94.60485
2013	98.34944
2014	102.99123
2015	107.03466