Year	Percent of Total
1960-01-01	56.2786980451824
1961-01-01	56.0791752112068
1962-01-01	55.6728954172003
1963-01-01	55.2268164515342
1964-01-01	54.9484753070300
1965-01-01	54.9080155588268
1966-01-01	54.6225324031649
1967-01-01	54.6183771759105
1968-01-01	54.7784123324492
1969-01-01	54.9417570011791
1970-01-01	55.0435028113302
1971-01-01	55.0018525996827
1972-01-01	55.0032896671906
1973-01-01	55.0537438852899
1974-01-01	55.2027526642267
1975-01-01	55.4858112344227
1976-01-01	55.8894578900614
1977-01-01	56.3932175746932
1978-01-01	56.9961423931484
1979-01-01	57.6758749337558
1980-01-01	58.4009992514592
1981-01-01	59.2055556396535
1982-01-01	59.9728868904505
1983-01-01	60.7115173621400
1984-01-01	61.4177850625980
1985-01-01	62.0704264350497
1986-01-01	62.4941184533042
1987-01-01	62.8779282863642
1988-01-01	63.2101802481133
1989-01-01	63.5050788095197
1990-01-01	63.7903139435158
1991-01-01	63.8498249004193
1992-01-01	64.0621979255953
1993-01-01	64.3506599369598
1994-01-01	64.6235665232198
1995-01-01	64.8520502352868
1996-01-01	65.3302843255043
1997-01-01	65.6534200552724
1998-01-01	65.9388224206871
1999-01-01	66.3402181343492
2000-01-01	66.9081224436695
2001-01-01	67.4218999562622
2002-01-01	68.0713028113055
2003-01-01	68.7938118646733
2004-01-01	69.4737031717588
2005-01-01	70.0456846338792
2006-01-01	70.4723727448300
2007-01-01	70.8368201559565
2008-01-01	71.1182351128376
2009-01-01	71.3126578802381
2010-01-01	71.4216823486363
2011-01-01	71.4509547361142
2012-01-01	71.3974904335600
2013-01-01	71.2719528076825
2014-01-01	71.0947317205226
2015-01-01	70.8801185369250
2016-01-01	70.5874449934751
2017-01-01	70.2805086620544