Year	Percent of Total
1960-01-01	59.0015038581244
1961-01-01	58.9752031606334
1962-01-01	58.8631249350125
1963-01-01	58.7412667990490
1964-01-01	58.7435158501441
1965-01-01	58.9534931642857
1966-01-01	58.9005971066176
1967-01-01	59.0405277719627
1968-01-01	59.3317252364512
1969-01-01	59.6417534337084
1970-01-01	59.8540300483359
1971-01-01	60.3772863083556
1972-01-01	60.7979818975454
1973-01-01	61.1618981028641
1974-01-01	61.5728153918774
1975-01-01	62.0870635186969
1976-01-01	62.4594279678029
1977-01-01	62.9581950356052
1978-01-01	63.5320038733037
1979-01-01	64.0852248021567
1980-01-01	64.5605540383708
1981-01-01	65.0951952314753
1982-01-01	65.5154748267417
1983-01-01	65.8538526984064
1984-01-01	66.1751699536125
1985-01-01	66.5078760162602
1986-01-01	66.4386061973823
1987-01-01	66.4288250429234
1988-01-01	66.4447701739948
1989-01-01	66.4158009632593
1990-01-01	66.3163697028628
1991-01-01	66.5404772461148
1992-01-01	66.6439825526757
1993-01-01	66.6771699857155
1994-01-01	66.7124131569271
1995-01-01	66.7787960942209
1996-01-01	66.7437998925299
1997-01-01	66.7732637136535
1998-01-01	66.8530356621345
1999-01-01	66.9374440738632
2000-01-01	66.9870917269705
2001-01-01	66.9334203123089
2002-01-01	66.8552386604106
2003-01-01	66.7676279154596
2004-01-01	66.7234554454641
2005-01-01	66.7577889251575
2006-01-01	66.8642932059200
2007-01-01	67.0598433535007
2008-01-01	67.3122399207991
2009-01-01	67.5678973496111
2010-01-01	67.7877892308801
2011-01-01	67.8199934129113
2012-01-01	67.8465035936307
2013-01-01	67.8464472630897
2014-01-01	67.7870996727601
2015-01-01	67.6480233309667
2016-01-01	67.4369844817575
2017-01-01	67.1203256168914