Year	Percent of Total
1960-01-01	45.2021055405042
1961-01-01	45.5276637767762
1962-01-01	45.7736656127952
1963-01-01	45.9554369251425
1964-01-01	46.1130183099807
1965-01-01	46.2632743023808
1966-01-01	46.4915013846549
1967-01-01	46.6984480444972
1968-01-01	46.8823139242905
1969-01-01	47.0465049770750
1970-01-01	47.1950445225686
1971-01-01	47.3954710480697
1972-01-01	47.5797810389005
1973-01-01	47.7455036470247
1974-01-01	47.8915758745554
1975-01-01	48.0192408863032
1976-01-01	48.2543594129187
1977-01-01	48.4357901395701
1978-01-01	48.5780332969788
1979-01-01	48.6932470478898
1980-01-01	48.7838348481534
1981-01-01	48.8129269439026
1982-01-01	48.8327490429997
1983-01-01	48.8306598614655
1984-01-01	48.8148111109804
1985-01-01	48.8070232666984
1986-01-01	48.6988640000654
1987-01-01	48.5650972274937
1988-01-01	48.4029103411056
1989-01-01	48.1806980335830
1990-01-01	47.8648622606002
1991-01-01	47.9380052234416
1992-01-01	47.9017343719993
1993-01-01	47.7565000946944
1994-01-01	47.5245653415788
1995-01-01	47.2204181550221
1996-01-01	46.8032032138070
1997-01-01	46.3345932997674
1998-01-01	45.7976489484985
1999-01-01	45.1725229503007
2000-01-01	44.4587118971085
2001-01-01	43.9569514048952
2002-01-01	43.4529525501189
2003-01-01	42.9651864277096
2004-01-01	42.5240604792645
2005-01-01	42.1435372777887
2006-01-01	41.5610157481299
2007-01-01	40.9988633508838
2008-01-01	40.4625260053309
2009-01-01	39.9528235966714
2010-01-01	39.4739795634177
2011-01-01	39.0686696189700
2012-01-01	38.6648164735554
2013-01-01	38.2828033372763
2014-01-01	37.9424089469746
2015-01-01	37.6465397180160
2016-01-01	37.3936972581301
2017-01-01	37.1857752838902