Year	Percent of Total
1960-01-01	53.2197638282133
1961-01-01	52.7784289865667
1962-01-01	52.3699703385969
1963-01-01	52.0256543796773
1964-01-01	51.7922376878672
1965-01-01	51.6865036091432
1966-01-01	51.4781060253342
1967-01-01	51.4208806790388
1968-01-01	51.4700110893888
1969-01-01	51.5716805037025
1970-01-01	51.7008357415563
1971-01-01	51.6790320954349
1972-01-01	51.7184981422477
1973-01-01	51.8023183995112
1974-01-01	51.9138148001580
1975-01-01	52.0401201149769
1976-01-01	52.0926129260992
1977-01-01	52.1514669273857
1978-01-01	52.2207249888988
1979-01-01	52.3034867478339
1980-01-01	52.3930797552651
1981-01-01	52.3604823079759
1982-01-01	52.3607485591204
1983-01-01	52.3816034744010
1984-01-01	52.4126246578068
1985-01-01	52.4555567027491
1986-01-01	52.4048739289574
1987-01-01	52.4066437506239
1988-01-01	52.4713781577883
1989-01-01	52.6175025771756
1990-01-01	52.8280179468295
1991-01-01	53.0958350896224
1992-01-01	53.4545208064466
1993-01-01	53.8964825393611
1994-01-01	54.4068568524117
1995-01-01	54.9746299040455
1996-01-01	55.6454559695767
1997-01-01	56.3478272139859
1998-01-01	57.0838548263737
1999-01-01	57.8555406872828
2000-01-01	58.6592580174692
2001-01-01	59.4647848438082
2002-01-01	60.2866069763789
2003-01-01	61.1097785411133
2004-01-01	61.9003472015856
2005-01-01	62.6206263614618
2006-01-01	63.1154967735419
2007-01-01	63.5519347107862
2008-01-01	63.9076165709454
2009-01-01	64.1657355026665
2010-01-01	64.3234343665237
2011-01-01	64.3308015436763
2012-01-01	64.2483741515953
2013-01-01	64.1065199447531
2014-01-01	63.9551735885148
2015-01-01	63.8273987213625
2016-01-01	63.6705484819052
2017-01-01	63.5953872626571