Year	Percent of Total
1960-01-01	55.7044572007429
1961-01-01	56.1968845413352
1962-01-01	56.7619927838899
1963-01-01	57.3618289936322
1964-01-01	58.0002072017405
1965-01-01	58.6489753235642
1966-01-01	59.3782876609388
1967-01-01	60.1436931456052
1968-01-01	60.8394759712879
1969-01-01	61.4320835894284
1970-01-01	61.9217634275070
1971-01-01	62.2722400857449
1972-01-01	62.8303736957421
1973-01-01	63.4999753938738
1974-01-01	64.1694425649300
1975-01-01	64.7454884954353
1976-01-01	64.8053337628569
1977-01-01	64.8854710786382
1978-01-01	64.9227197243002
1979-01-01	64.8848343748326
1980-01-01	64.7565635124567
1981-01-01	66.3308401573280
1982-01-01	67.4973683831057
1983-01-01	68.3623121439581
1984-01-01	69.0940241027368
1985-01-01	69.8017413987782
1986-01-01	69.5339907320849
1987-01-01	69.6029985248886
1988-01-01	69.8497501092849
1989-01-01	70.1316387728149
1990-01-01	70.4127443881246
1991-01-01	70.7393572394157
1992-01-01	70.9279399092261
1993-01-01	71.0209623459325
1994-01-01	71.1316420000197
1995-01-01	71.3133575483733
1996-01-01	71.5271183065801
1997-01-01	71.8496543261605
1998-01-01	72.1862907181658
1999-01-01	72.4432651326638
2000-01-01	72.5887142116647
2001-01-01	73.8888546668266
2002-01-01	74.9609313894796
2003-01-01	75.8047651273770
2004-01-01	76.4803552720876
2005-01-01	77.0476942590907
2006-01-01	80.2244101735779
2007-01-01	82.5727766462430
2008-01-01	84.1681889700304
2009-01-01	85.1968216849596
2010-01-01	85.8716979944664
2011-01-01	85.6769843457199
2012-01-01	85.6155383471877
2013-01-01	85.4797191523738
2014-01-01	85.2672169486515
2015-01-01	85.0838935031849
2016-01-01	84.9299790956820
2017-01-01	84.8158029047318