Year	Percent of Total
1960-01-01	55.1936557664652
1961-01-01	54.8818644821501
1962-01-01	54.6356215549569
1963-01-01	54.4623654589183
1964-01-01	54.3666167455326
1965-01-01	54.3396100096063
1966-01-01	54.1841518943842
1967-01-01	54.1023256801833
1968-01-01	54.0789700316775
1969-01-01	54.0906984434374
1970-01-01	54.1299580535515
1971-01-01	54.2759006421908
1972-01-01	54.4272652264463
1973-01-01	54.5933210178770
1974-01-01	54.7960702604429
1975-01-01	55.0434776684894
1976-01-01	55.2392617196611
1977-01-01	55.4787810212510
1978-01-01	55.7255050027039
1979-01-01	55.9399039323920
1980-01-01	56.1114130188413
1981-01-01	56.2588606595969
1982-01-01	56.3733068086608
1983-01-01	56.4642560986065
1984-01-01	56.5667174464825
1985-01-01	56.7044394343094
1986-01-01	56.7668521780948
1987-01-01	56.9032249576420
1988-01-01	57.0720617506221
1989-01-01	57.2297799979753
1990-01-01	57.3681930598873
1991-01-01	57.4766415021907
1992-01-01	57.5632407357051
1993-01-01	57.6581665717906
1994-01-01	57.8079616479148
1995-01-01	58.0215072256066
1996-01-01	58.1544139965180
1997-01-01	58.3622113376809
1998-01-01	58.6142268469066
1999-01-01	58.8844381509390
2000-01-01	59.1559946620677
2001-01-01	59.5077743192684
2002-01-01	59.8680148906111
2003-01-01	60.2376973351822
2004-01-01	60.6270037506754
2005-01-01	61.0404573907060
2006-01-01	61.5912862162961
2007-01-01	62.1434215790807
2008-01-01	62.6736247678441
2009-01-01	63.1586891546776
2010-01-01	63.5852503329740
2011-01-01	63.8308582697912
2012-01-01	64.0685156452358
2013-01-01	64.2718360810109
2014-01-01	64.4317941713190
2015-01-01	64.5579412526938
2016-01-01	64.6300138157549
2017-01-01	64.6886339982150