Year	Percent of Total
1960-01-01	41.6087935321278
1961-01-01	41.7917107051759
1962-01-01	41.8865431092297
1963-01-01	41.9274917937421
1964-01-01	41.9479685539856
1965-01-01	41.9613306257156
1966-01-01	42.1760208291880
1967-01-01	42.3358914018947
1968-01-01	42.4548150488904
1969-01-01	42.5446127222321
1970-01-01	42.6149363895865
1971-01-01	42.8402601194760
1972-01-01	43.0332711284564
1973-01-01	43.1951621443153
1974-01-01	43.3257921761901
1975-01-01	43.4313896650799
1976-01-01	43.6679391660064
1977-01-01	43.8229505694382
1978-01-01	43.9251892852942
1979-01-01	44.0003227284449
1980-01-01	44.0555023661351
1981-01-01	44.3650924785903
1982-01-01	44.6213474344005
1983-01-01	44.8239722604476
1984-01-01	44.9659137169437
1985-01-01	45.0430541552600
1986-01-01	45.1842272893554
1987-01-01	45.2343502664900
1988-01-01	45.2070790139392
1989-01-01	45.1168764135822
1990-01-01	44.9728659564857
1991-01-01	44.9313763703153
1992-01-01	44.8261278862714
1993-01-01	44.6674251915380
1994-01-01	44.4676492034614
1995-01-01	44.2389842596802
1996-01-01	44.1632678575828
1997-01-01	44.0445732860224
1998-01-01	43.8992479749454
1999-01-01	43.7469005881004
2000-01-01	43.6015129101803
2001-01-01	43.6387959857690
2002-01-01	43.6565915146194
2003-01-01	43.6639092166247
2004-01-01	43.6665211748241
2005-01-01	43.6680717916617
2006-01-01	43.7949765329645
2007-01-01	43.8853824812066
2008-01-01	43.9495584193380
2009-01-01	43.9968312364707
2010-01-01	44.0304525725629
2011-01-01	44.1174834204416
2012-01-01	44.1790077118048
2013-01-01	44.2062708012032
2014-01-01	44.1862196447792
2015-01-01	44.1149688900224
2016-01-01	44.0873771248764
2017-01-01	43.9916589932947