Year	Percent of Total
1960-01-01	55.5685286650580
1961-01-01	55.3499936662701
1962-01-01	55.2302295980747
1963-01-01	55.1777320594169
1964-01-01	55.1623985125849
1965-01-01	55.1709915496201
1966-01-01	54.9385902541363
1967-01-01	54.7767680437029
1968-01-01	54.6685101242332
1969-01-01	54.5987219449406
1970-01-01	54.5555898923571
1971-01-01	54.3149680400857
1972-01-01	54.1172712707617
1973-01-01	53.9602251742223
1974-01-01	53.8429702102971
1975-01-01	53.7580365518926
1976-01-01	53.5146190959468
1977-01-01	53.3608293466098
1978-01-01	53.2661481479878
1979-01-01	53.2029481467557
1980-01-01	53.1622952695103
1981-01-01	52.8266399895965
1982-01-01	52.5508717518500
1983-01-01	52.3347927721729
1984-01-01	52.1848882212548
1985-01-01	52.1043446437349
1986-01-01	51.9441145686742
1987-01-01	51.8825736114661
1988-01-01	51.9052483651212
1989-01-01	51.9971139224806
1990-01-01	52.1480846622968
1991-01-01	52.1755791425817
1992-01-01	52.2757313214124
1993-01-01	52.4369084963988
1994-01-01	52.6456720463081
1995-01-01	52.8887484305485
1996-01-01	52.9605238204536
1997-01-01	53.0846943789791
1998-01-01	53.2431238360366
1999-01-01	53.4145222853157
2000-01-01	53.5834773256563
2001-01-01	53.5455764744969
2002-01-01	53.5365099488438
2003-01-01	53.5457419764763
2004-01-01	53.5656791971639
2005-01-01	53.5911218840192
2006-01-01	53.4503882905150
2007-01-01	53.3535355834032
2008-01-01	53.2901868133527
2009-01-01	53.2510528462030
2010-01-01	53.2320732158868
2011-01-01	53.1294004811334
2012-01-01	53.0611184339370
2013-01-01	53.0350123110259
2014-01-01	53.0633739214909
2015-01-01	53.1488409781506
2016-01-01	53.1654897552358
2017-01-01	53.2576351166428