Year	Percent of Total
1960-01-01	54.2253287574651
1961-01-01	53.5650464076336
1962-01-01	52.9675167785235
1963-01-01	52.4709183718398
1964-01-01	52.0431254572415
1965-01-01	51.6071597354843
1966-01-01	50.9225036286753
1967-01-01	50.1546811427659
1968-01-01	49.3890064432446
1969-01-01	48.7259207511136
1970-01-01	48.2300929784401
1971-01-01	48.2429244292065
1972-01-01	48.4106080747229
1973-01-01	48.7353434687548
1974-01-01	49.1935072175949
1975-01-01	49.7528525642132
1976-01-01	50.7406749599165
1977-01-01	51.6424117223526
1978-01-01	52.4149626911036
1979-01-01	53.0352278108867
1980-01-01	53.5252849570860
1981-01-01	54.0344551263820
1982-01-01	54.4986482962000
1983-01-01	54.9560049717065
1984-01-01	55.4562750899003
1985-01-01	56.0190589565380
1986-01-01	56.3921209965618
1987-01-01	56.8267529785284
1988-01-01	57.2593913435113
1989-01-01	57.5949030618178
1990-01-01	57.7956738642429
1991-01-01	58.1457787795419
1992-01-01	58.3914654318514
1993-01-01	58.5771674658528
1994-01-01	58.7797532001963
1995-01-01	59.0318588813923
1996-01-01	59.2415748208524
1997-01-01	59.4451039826011
1998-01-01	59.6383043823407
1999-01-01	59.8169861117120
2000-01-01	59.9950166813205
2001-01-01	60.3047951614693
2002-01-01	60.6698112297557
2003-01-01	61.0679182499168
2004-01-01	61.4649346575407
2005-01-01	61.8470761362100
2006-01-01	62.3834764529238
2007-01-01	62.8845163714791
2008-01-01	63.3969052249328
2009-01-01	63.9674232065966
2010-01-01	64.5942262025195
2011-01-01	65.1100391483563
2012-01-01	65.7056760455503
2013-01-01	66.3247898613055
2014-01-01	66.8610003818892
2015-01-01	67.2429449980396
2016-01-01	67.5307624364231
2017-01-01	67.5891663803641