Year	Percent of Total
1960-01-01	51.4377377695691
1961-01-01	51.1867574478056
1962-01-01	50.9310748571596
1963-01-01	50.7231623911165
1964-01-01	50.6400326389799
1965-01-01	50.7052156635007
1966-01-01	50.6558846298926
1967-01-01	50.7435072100987
1968-01-01	50.9293877662444
1969-01-01	51.1532130933021
1970-01-01	51.3790264741207
1971-01-01	51.3660284267051
1972-01-01	51.3843065305836
1973-01-01	51.4200601848136
1974-01-01	51.4608195916638
1975-01-01	51.4995660369851
1976-01-01	51.3250062810511
1977-01-01	51.1569849217709
1978-01-01	51.0089551257257
1979-01-01	50.8917141431817
1980-01-01	50.8073705089848
1981-01-01	50.6327606767733
1982-01-01	50.5041334092942
1983-01-01	50.4240346445327
1984-01-01	50.3931357071961
1985-01-01	50.4107130287886
1986-01-01	50.3906096316405
1987-01-01	50.4394782424297
1988-01-01	50.5419744814152
1989-01-01	50.6657613724820
1990-01-01	50.7887842727395
1991-01-01	50.9058689671390
1992-01-01	50.9759856884823
1993-01-01	51.0428233413411
1994-01-01	51.1561253077845
1995-01-01	51.3310625586480
1996-01-01	51.4333584366348
1997-01-01	51.6234289286359
1998-01-01	51.8648716158556
1999-01-01	52.0955584966738
2000-01-01	52.2861245845007
2001-01-01	52.5424685361259
2002-01-01	52.7514962918696
2003-01-01	52.9563269500574
2004-01-01	53.2218794749520
2005-01-01	53.5776725584276
2006-01-01	54.0098132359106
2007-01-01	54.5443795844846
2008-01-01	55.1462242240421
2009-01-01	55.7567059657138
2010-01-01	56.3434999836300
2011-01-01	56.9960409846357
2012-01-01	57.5868230723534
2013-01-01	58.1412194010675
2014-01-01	58.6959674027647
2015-01-01	59.2610003095537
2016-01-01	59.7483040673859
2017-01-01	60.2550163617791