Year	Percent of Total
1960-01-01	53.3680719179324
1961-01-01	52.9534953707801
1962-01-01	52.6341340372894
1963-01-01	52.3680667766356
1964-01-01	52.1183733599173
1965-01-01	51.8706130631719
1966-01-01	51.5225006736729
1967-01-01	51.2074338111765
1968-01-01	50.9260635347125
1969-01-01	50.6970637553962
1970-01-01	50.5277321883479
1971-01-01	50.6091674866784
1972-01-01	50.7634762739524
1973-01-01	50.9433190704729
1974-01-01	51.0766698180886
1975-01-01	51.1206923917628
1976-01-01	51.5050585537162
1977-01-01	51.7691612259257
1978-01-01	51.9486831913246
1979-01-01	52.0872315229248
1980-01-01	52.1939501671462
1981-01-01	52.0681442617364
1982-01-01	52.0113385592403
1983-01-01	51.9874042775790
1984-01-01	51.9739329190533
1985-01-01	51.9877310521704
1986-01-01	51.9618110601883
1987-01-01	51.9629425680181
1988-01-01	52.0102305204169
1989-01-01	52.1609731443405
1990-01-01	52.4646830301960
1991-01-01	53.4996575615531
1992-01-01	54.6125427764251
1993-01-01	55.8064215671844
1994-01-01	57.0628850489754
1995-01-01	58.3569804784594
1996-01-01	58.6383930367788
1997-01-01	59.0720041533079
1998-01-01	59.5475770191507
1999-01-01	60.0085679390559
2000-01-01	60.4631147125363
2001-01-01	61.1664612009742
2002-01-01	61.9856187226495
2003-01-01	62.9157469536800
2004-01-01	63.9184931307933
2005-01-01	64.9354967548279
2006-01-01	66.8136667917155
2007-01-01	68.4510294198280
2008-01-01	69.7797111576817
2009-01-01	70.8200164970367
2010-01-01	71.6222800891677
2011-01-01	72.8628584349519
2012-01-01	73.8763636321654
2013-01-01	74.6203200285816
2014-01-01	75.1343183726024
2015-01-01	75.5133446513056
2016-01-01	75.6396389229522
2017-01-01	75.8323839334360