Year	Percent
1972	29.63101
1973	31.7205
1974	33.0964
1975	38.57183
1976	44.13897
1977	47.44456
1978	49.91722
1979	50.63688
1980	51.63813
1981	54.23341
1982	57.9462
1983	60.33237
1984	63.61826
1985	74.43635
1986	62.60965
1987	65.35248
1988	66.71367
1989	69.65659
1990	69.12355
1991	70.14467
1992	73.36825
1993	73.31807
1994	73.22049
1995	75.58901
1996	79.40558
1997	81.12051
1999	81.02559
2000	79.47821
2001	85.62084
2002	87.61409
2003	89.10669
2004	91.51132
2005	92.79709
2006	82.734
2007	95.22839
2008	107.00366
2009	92.65098
2010	95.25702
2011	97.20807
2012	101.15859
2013	105.70069
2014	108.75278
2015	105.33353
2016	105.37186