Year	Percent
1971	35.40469
1972	38.73159
1973	40.05781
1974	45.12329
1975	47.62613
1976	51.67123
1977	55.43339
1978	58.49584
1979	56.90937
1980	56.96336
1981	59.83125
1982	64.57577
1983	67.65515
1984	71.12017
1985	75.09176
1986	78.31904
1987	79.28619
1988	79.82027
1989	84.84206
1990	84.59758
1991	86.36807
1992	90.77773
1993	83.11526
1994	85.43516
1995	85.80384
1996	88.01019
1997	87.29425
1998	87.60179
1999	88.18319
2000	87.93027
2001	89.48542
2002	91.38344
2003	105.07477
2004	106.10139
2005	108.05334
2006	108.59494
2007	105.96514
2008	104.61059
2009	103.72827
2010	103.53944
2011	107.7214
2012	108.63822
2013	65.48248