Year	Percent
1970	22.60594
1971	27.6753
1972	28.52096
1973	29.11836
1974	34.42556
1975	41.19114
1976	34.31403
1977	52.30803
1978	55.34106
1979	59.55812
1980	64.76191
1981	67.28875
1982	71.87399
1983	76.23571
1984	76.06803
1985	82.14041
1986	85.54573
1987	87.28945
1988	90.88393
1989	102.78051
1990	136.46463
1991	124.24648
1992	128.32058
1993	134.96799
1994	147.56701
1995	134.57436
1996	127.29369
1997	111.0612
1998	102.12591
1999	107.17052
2000	81.56388
2001	70.55965
2002	73.41722
2003	72.73312
2004	74.568
2005	56.08203
2006	38.66675
2007	25.25447
2008	26.06658
2009	26.61534
2010	26.31706
2011	26.16546
2012	29.30942
2013	39.72396
2014	40.33747
2015	38.99158
2016	37.8156