Year	Percent of Total
1960-01-01	51.0840183765865
1961-01-01	50.4333765976637
1962-01-01	49.8512227965770
1963-01-01	49.3484940952259
1964-01-01	48.8588183179699
1965-01-01	48.3115615459700
1966-01-01	47.9112391577528
1967-01-01	47.4052267223969
1968-01-01	46.7547613635241
1969-01-01	46.0150463751472
1970-01-01	45.3004992319509
1971-01-01	45.9047347945725
1972-01-01	46.5022779578226
1973-01-01	47.1293246236019
1974-01-01	47.7886706224892
1975-01-01	48.4335285918611
1976-01-01	48.9551111430832
1977-01-01	49.4633567016157
1978-01-01	49.9895238594102
1979-01-01	50.5322899647433
1980-01-01	51.0776610982566
1981-01-01	51.8888907470274
1982-01-01	52.5900919490896
1983-01-01	53.1635978491119
1984-01-01	53.5840537326863
1985-01-01	53.8515084877154
1986-01-01	54.6956514978347
1987-01-01	55.2871773738114
1988-01-01	55.6723806100365
1989-01-01	55.8938185883668
1990-01-01	55.9887107862648
1991-01-01	56.3964439624418
1992-01-01	56.6919147437027
1993-01-01	56.9191655347752
1994-01-01	57.1261368565272
1995-01-01	57.3440602812763
1996-01-01	57.7286515798233
1997-01-01	58.2105555776181
1998-01-01	58.7832853515077
1999-01-01	59.4398473951486
2000-01-01	60.1819699392796
2001-01-01	60.9974505250404
2002-01-01	61.9148363513454
2003-01-01	62.9074441055332
2004-01-01	63.9379726473181
2005-01-01	64.9565706048353
2006-01-01	65.7777482210547
2007-01-01	66.4787671560423
2008-01-01	67.1019973998345
2009-01-01	67.6550385330542
2010-01-01	68.1208714798934
2011-01-01	68.7594919232362
2012-01-01	69.3356593359453
2013-01-01	69.8736194922009
2014-01-01	70.3873121680525
2015-01-01	70.8610317935059
2016-01-01	71.1293992079319
2017-01-01	71.3951823935944