Year	Percent of Total
1960-01-01	63.6049766664088
1961-01-01	63.5669292579561
1962-01-01	63.6650632503198
1963-01-01	63.8701323651716
1964-01-01	64.1203366305529
1965-01-01	64.3735702674928
1966-01-01	64.6948739737092
1967-01-01	64.9472632851632
1968-01-01	65.1655592592798
1969-01-01	65.3990475219512
1970-01-01	65.6559754208562
1971-01-01	65.7024500645113
1972-01-01	65.8367182146312
1973-01-01	65.9856953422904
1974-01-01	66.0449129335512
1975-01-01	65.9695610913510
1976-01-01	65.7717313561982
1977-01-01	65.4471810139287
1978-01-01	65.0819670765768
1979-01-01	64.8264196002186
1980-01-01	64.7596025661928
1981-01-01	64.7553536701588
1982-01-01	64.9553477537912
1983-01-01	65.2644360868895
1984-01-01	65.5338615311373
1985-01-01	65.6866027367411
1986-01-01	65.7616549179199
1987-01-01	65.7196166068605
1988-01-01	65.6384551847220
1989-01-01	65.6298312735477
1990-01-01	65.7496920600127
1991-01-01	65.7753183402017
1992-01-01	65.9464300542358
1993-01-01	66.2218665516945
1994-01-01	66.5250097712484
1995-01-01	66.8215432517869
1996-01-01	67.0866514952688
1997-01-01	67.3451688808050
1998-01-01	67.6076187602265
1999-01-01	67.9015855883218
2000-01-01	68.2361069706522
2001-01-01	68.5109098429030
2002-01-01	68.7973347567623
2003-01-01	69.0894861818537
2004-01-01	69.3777525179075
2005-01-01	69.6459978253194
2006-01-01	69.7822648853586
2007-01-01	69.8931490002307
2008-01-01	69.9587954154736
2009-01-01	69.9551180509448
2010-01-01	69.8692401866477
2011-01-01	69.6112077760575
2012-01-01	69.3238934386261
2013-01-01	68.9938024709569
2014-01-01	68.6038951395013
2015-01-01	68.1551241674716
2016-01-01	67.7070099793078
2017-01-01	67.1869896342948