Year	Percent of Total
1960-01-01	9.49456875607181
1961-01-01	9.62585194862534
1962-01-01	9.75638065451180
1963-01-01	9.88797662093452
1964-01-01	10.01991031444310
1965-01-01	10.15554934880980
1966-01-01	10.32476596913920
1967-01-01	10.50071629042610
1968-01-01	10.68717584347130
1969-01-01	10.88626011551350
1970-01-01	11.09810593888620
1971-01-01	11.31537705424270
1972-01-01	11.51529455929170
1973-01-01	11.71047616274910
1974-01-01	11.92016832182230
1975-01-01	12.15359597694550
1976-01-01	12.42543762857710
1977-01-01	12.72842930373010
1978-01-01	13.02012727218400
1979-01-01	13.23158117439570
1980-01-01	13.32779019256500
1981-01-01	13.36378613991420
1982-01-01	13.27931997058520
1983-01-01	13.14791029171600
1984-01-01	13.07579275908520
1985-01-01	13.12247212674190
1986-01-01	13.36434626882750
1987-01-01	13.70211284743310
1988-01-01	14.09817864968800
1989-01-01	14.49363534592790
1990-01-01	14.85528939669990
1991-01-01	15.23115797736710
1992-01-01	15.58340521647150
1993-01-01	15.91674242245920
1994-01-01	16.24059037751880
1995-01-01	16.56176759372730
1996-01-01	16.88681238245830
1997-01-01	17.19749938886840
1998-01-01	17.50370589377520
1999-01-01	17.81821084295770
2000-01-01	18.14788220859320
2001-01-01	18.44382727220450
2002-01-01	18.74720153432000
2003-01-01	19.04417416832430
2004-01-01	19.31264067940240
2005-01-01	19.54339818627870
2006-01-01	19.75353059770660
2007-01-01	19.91737599212430
2008-01-01	20.06641750578570
2009-01-01	20.24919648287920
2010-01-01	20.49816099355550
2011-01-01	20.80665959291890
2012-01-01	21.17345924924220
2013-01-01	21.58001776496610
2014-01-01	21.98547979692030
2015-01-01	22.36287071577390
2016-01-01	22.70931866023480
2017-01-01	23.02124329724270