Year	Percent of Total
1960-01-01	63.6953888571626
1961-01-01	63.6189090509237
1962-01-01	63.5728070346034
1963-01-01	63.5569313249936
1964-01-01	63.5709808481206
1965-01-01	63.6113445934393
1966-01-01	63.5966219801291
1967-01-01	63.6146819387566
1968-01-01	63.6502560177476
1969-01-01	63.6798071607851
1970-01-01	63.6859636346769
1971-01-01	63.6284235049693
1972-01-01	63.5540548463381
1973-01-01	63.4601149198989
1974-01-01	63.3407444073986
1975-01-01	63.1893420698029
1976-01-01	62.8825147055091
1977-01-01	62.5179357603354
1978-01-01	62.1270727660330
1979-01-01	61.7640051300846
1980-01-01	61.4622743817950
1981-01-01	61.0854207654010
1982-01-01	60.8779365183546
1983-01-01	60.7698055233083
1984-01-01	60.6675754181759
1985-01-01	60.5329802118104
1986-01-01	60.5153266442071
1987-01-01	60.4009554474900
1988-01-01	60.2704337218357
1989-01-01	60.2342097327694
1990-01-01	60.3333072714084
1991-01-01	60.3695683046515
1992-01-01	60.5488889353074
1993-01-01	60.8162923324518
1994-01-01	61.0863468681668
1995-01-01	61.3188142677369
1996-01-01	61.4835700670605
1997-01-01	61.6393679416310
1998-01-01	61.7866241519757
1999-01-01	61.9393960958597
2000-01-01	62.1035871543462
2001-01-01	62.2915426224228
2002-01-01	62.4549312907552
2003-01-01	62.6106546911136
2004-01-01	62.7805335867750
2005-01-01	62.9708563091613
2006-01-01	63.0958957645172
2007-01-01	63.2672211194013
2008-01-01	63.4542374399890
2009-01-01	63.6126696645370
2010-01-01	63.7214844043462
2011-01-01	63.7967765179912
2012-01-01	63.8270413297334
2013-01-01	63.8314501024626
2014-01-01	63.8431497819469
2015-01-01	63.8777606355371
2016-01-01	63.8805193371653
2017-01-01	63.9162381566767