Year	Percent of Total
1960-01-01	53.4447800430685
1961-01-01	53.0414245132305
1962-01-01	52.7395196079078
1963-01-01	52.5116023657715
1964-01-01	52.3312653632125
1965-01-01	52.1908729330984
1966-01-01	51.9170510880904
1967-01-01	51.7085659221923
1968-01-01	51.5659621828692
1969-01-01	51.4972378265405
1970-01-01	51.5012516232806
1971-01-01	51.3610842010763
1972-01-01	51.3127483186788
1973-01-01	51.3362586671388
1974-01-01	51.4082848488135
1975-01-01	51.5156327379080
1976-01-01	51.4730217181951
1977-01-01	51.4963380217644
1978-01-01	51.5678528376555
1979-01-01	51.6700288406772
1980-01-01	51.7932187590649
1981-01-01	51.7734705225918
1982-01-01	51.7920478683473
1983-01-01	51.8417981268714
1984-01-01	51.9198494664147
1985-01-01	52.0231171416916
1986-01-01	51.9758191690559
1987-01-01	51.9691305830427
1988-01-01	51.9974498206450
1989-01-01	52.0551813484613
1990-01-01	52.1392120740442
1991-01-01	52.1460270995328
1992-01-01	52.1964841497213
1993-01-01	52.2821031634369
1994-01-01	52.3922096150045
1995-01-01	52.5191495761847
1996-01-01	52.7176404581092
1997-01-01	52.9385037534421
1998-01-01	53.1763600124430
1999-01-01	53.4310482755840
2000-01-01	53.7021487370260
2001-01-01	53.8752060841450
2002-01-01	54.0790358440054
2003-01-01	54.3039385996564
2004-01-01	54.5384992817525
2005-01-01	54.7758023713395
2006-01-01	54.9401317062099
2007-01-01	55.1207260619471
2008-01-01	55.3120857533335
2009-01-01	55.5086747009943
2010-01-01	55.7048911732039
2011-01-01	55.8771725961839
2012-01-01	56.0597654611109
2013-01-01	56.2490718848909
2014-01-01	56.4483306758007
2015-01-01	56.6607074841578
2016-01-01	56.7773024897827
2017-01-01	56.9339873634220