Year	Percent of Total
1960-01-01	53.0846371508040
1961-01-01	52.9962311541104
1962-01-01	52.8801122014373
1963-01-01	52.7800030408379
1964-01-01	52.7801171527820
1965-01-01	52.9159163659322
1966-01-01	52.8756452478262
1967-01-01	52.9837802755406
1968-01-01	53.1892682439483
1969-01-01	53.4217269841557
1970-01-01	53.6453416036032
1971-01-01	53.6576496367532
1972-01-01	53.7053517360166
1973-01-01	53.7733908595357
1974-01-01	53.8567629669158
1975-01-01	53.9546882900997
1976-01-01	53.8794917724855
1977-01-01	53.8286371130660
1978-01-01	53.8033224916183
1979-01-01	53.8130336436024
1980-01-01	53.8652759825210
1981-01-01	53.7801936025271
1982-01-01	53.7585631433604
1983-01-01	53.7821394774462
1984-01-01	53.8338699097001
1985-01-01	53.9097004773366
1986-01-01	53.9259971728775
1987-01-01	53.9779220546188
1988-01-01	54.0599901073704
1989-01-01	54.1693452640366
1990-01-01	54.3048934664519
1991-01-01	54.4473731290904
1992-01-01	54.6214251370675
1993-01-01	54.8243049564706
1994-01-01	55.0534509273054
1995-01-01	55.3055394983873
1996-01-01	55.5210968192444
1997-01-01	55.7686934900973
1998-01-01	56.0383212392730
1999-01-01	56.3228914814551
2000-01-01	56.6198357889526
2001-01-01	56.8607906312987
2002-01-01	57.1315601076809
2003-01-01	57.4172173403765
2004-01-01	57.7023801200324
2005-01-01	57.9814230792285
2006-01-01	58.2438486000827
2007-01-01	58.5010830970347
2008-01-01	58.7635750748319
2009-01-01	59.0485070420919
2010-01-01	59.3628286141838
2011-01-01	59.6836106887809
2012-01-01	60.0401367164228
2013-01-01	60.4116780112505
2014-01-01	60.7675002809558
2015-01-01	61.0892980273117
2016-01-01	61.3888725098233
2017-01-01	61.6565293713128