Year	Percent of Total
1960-01-01	62.1078516373221
1961-01-01	61.7359362197635
1962-01-01	61.5040737390182
1963-01-01	61.4101557078859
1964-01-01	61.4193337871421
1965-01-01	61.5067703031782
1966-01-01	61.6245533746095
1967-01-01	61.8302305813523
1968-01-01	62.0983092497058
1969-01-01	62.3884429503210
1970-01-01	62.6711714433855
1971-01-01	62.9785568375090
1972-01-01	63.2349725776865
1973-01-01	63.4499264484791
1974-01-01	63.6464529814966
1975-01-01	63.8344749972657
1976-01-01	63.8471313454735
1977-01-01	63.9066369833363
1978-01-01	63.9956477424065
1979-01-01	64.0924245054125
1980-01-01	64.1881605942049
1981-01-01	64.2916568708811
1982-01-01	64.3821146974184
1983-01-01	64.4531538322417
1984-01-01	64.5127945702325
1985-01-01	64.5606013864519
1986-01-01	64.4942557266880
1987-01-01	64.4408840008247
1988-01-01	64.3987666933150
1989-01-01	64.3610875972628
1990-01-01	64.3316759306038
1991-01-01	64.1875727191168
1992-01-01	64.1100998821792
1993-01-01	64.1101713518066
1994-01-01	64.1993275887757
1995-01-01	64.3844456035001
1996-01-01	64.7310890390780
1997-01-01	65.1189679971543
1998-01-01	65.5453280506856
1999-01-01	65.9982732805843
2000-01-01	66.4530413561837
2001-01-01	66.7428867808978
2002-01-01	67.0393803955966
2003-01-01	67.3583522107988
2004-01-01	67.7117767611913
2005-01-01	68.1021218610914
2006-01-01	68.3983706165416
2007-01-01	68.7226571447464
2008-01-01	69.0181528324659
2009-01-01	69.2277167788675
2010-01-01	69.3212622083294
2011-01-01	69.2433078300192
2012-01-01	69.0827843090671
2013-01-01	68.8519746938240
2014-01-01	68.5747223104379
2015-01-01	68.2683632595082
2016-01-01	67.8537918770795
2017-01-01	67.4494312397514