Year	Percent of Total
1960-01-01	56.3756828922131
1961-01-01	56.0981243712129
1962-01-01	55.7603124392828
1963-01-01	55.4426956179619
1964-01-01	55.2462974995770
1965-01-01	55.2045618555388
1966-01-01	55.0077609681378
1967-01-01	54.9960763550829
1968-01-01	55.1016691058473
1969-01-01	55.2321465452463
1970-01-01	55.3463292842634
1971-01-01	55.3434817954048
1972-01-01	55.3718035147923
1973-01-01	55.4333558692961
1974-01-01	55.5523830643452
1975-01-01	55.7429893220901
1976-01-01	55.9043305133136
1977-01-01	56.1371066764466
1978-01-01	56.4302780915110
1979-01-01	56.7632961560402
1980-01-01	57.1171966239821
1981-01-01	57.4348738131874
1982-01-01	57.7514448216861
1983-01-01	58.0676005959883
1984-01-01	58.3835628089483
1985-01-01	58.6929373357471
1986-01-01	58.8435078728978
1987-01-01	59.0128740379236
1988-01-01	59.1895039876635
1989-01-01	59.3717271247673
1990-01-01	59.5628906903584
1991-01-01	59.6313914713175
1992-01-01	59.7859841710536
1993-01-01	59.9979159107170
1994-01-01	60.2335996995599
1995-01-01	60.4811088531754
1996-01-01	60.8009948704964
1997-01-01	61.0845594982869
1998-01-01	61.3725748056307
1999-01-01	61.7169692237894
2000-01-01	62.1306976543100
2001-01-01	62.4643748551296
2002-01-01	62.8633555369855
2003-01-01	63.2990778132110
2004-01-01	63.7216056151618
2005-01-01	64.1025163002084
2006-01-01	64.3789620951506
2007-01-01	64.6328751956181
2008-01-01	64.8543081224902
2009-01-01	65.0422156800109
2010-01-01	65.1968536838333
2011-01-01	65.2850660008900
2012-01-01	65.3503590000900
2013-01-01	65.3925567611347
2014-01-01	65.4133530842537
2015-01-01	65.4151122196177
2016-01-01	65.3623154372075
2017-01-01	65.3048533956161