Year	Percent of Total
1960-01-01	58.8761891181780
1961-01-01	58.8236403348807
1962-01-01	58.7508153701637
1963-01-01	58.7381978766790
1964-01-01	58.8627748232103
1965-01-01	59.1404264765930
1966-01-01	59.4024372644789
1967-01-01	59.8012513302499
1968-01-01	60.2416184118320
1969-01-01	60.5702297739736
1970-01-01	60.7000507435723
1971-01-01	60.6978385026840
1972-01-01	60.5219580463835
1973-01-01	60.2364080964402
1974-01-01	59.9478695120299
1975-01-01	59.7120560064254
1976-01-01	59.2942307063936
1977-01-01	58.9643631801531
1978-01-01	58.7045498552228
1979-01-01	58.4877162800351
1980-01-01	58.3124213715131
1981-01-01	58.2749358361432
1982-01-01	58.2722088278335
1983-01-01	58.3113234701805
1984-01-01	58.4021433569133
1985-01-01	58.5410897017160
1986-01-01	58.7652864125009
1987-01-01	59.0004836132432
1988-01-01	59.2572518813601
1989-01-01	59.5417113805794
1990-01-01	59.8457496153184
1991-01-01	60.1280841351155
1992-01-01	60.4452034141994
1993-01-01	60.7659997634194
1994-01-01	61.0427032375855
1995-01-01	61.2507520549920
1996-01-01	61.4689261830692
1997-01-01	61.6204010836105
1998-01-01	61.7211341824496
1999-01-01	61.8077929043394
2000-01-01	61.8991905371382
2001-01-01	61.9291854350986
2002-01-01	61.9913980528217
2003-01-01	62.0628901181334
2004-01-01	62.1118944748406
2005-01-01	62.1241653377192
2006-01-01	62.2664932301893
2007-01-01	62.3529309798149
2008-01-01	62.3852785734514
2009-01-01	62.3637655744889
2010-01-01	62.2794712440508
2011-01-01	62.0408536441965
2012-01-01	61.7665949483739
2013-01-01	61.4708279712394
2014-01-01	61.1797974872972
2015-01-01	60.9170856093963
2016-01-01	60.6244662363516
2017-01-01	60.4044308946509