Year	Percent of Total
1960-01-01	52.9105010527739
1961-01-01	52.6117843428202
1962-01-01	52.3471065239388
1963-01-01	52.1346270688243
1964-01-01	52.0077847605025
1965-01-01	51.9784011983100
1966-01-01	51.8231435791254
1967-01-01	51.8012906932229
1968-01-01	51.8729459023516
1969-01-01	51.9934335963885
1970-01-01	52.1427031072248
1971-01-01	52.1975783575051
1972-01-01	52.3091529877187
1973-01-01	52.4686786389037
1974-01-01	52.6700043504815
1975-01-01	52.9059227848922
1976-01-01	53.0535263618357
1977-01-01	53.2246440719734
1978-01-01	53.4335131294894
1979-01-01	53.7065326743616
1980-01-01	54.0542204904396
1981-01-01	54.2926142847773
1982-01-01	54.6557805915044
1983-01-01	55.0889236850216
1984-01-01	55.5179788209000
1985-01-01	55.9071609063740
1986-01-01	56.2622207270532
1987-01-01	56.5528016972664
1988-01-01	56.8199314248111
1989-01-01	57.1280197974070
1990-01-01	57.5033200226989
1991-01-01	57.7725577845265
1992-01-01	58.1282906634878
1993-01-01	58.5343536131546
1994-01-01	58.9373943980522
1995-01-01	59.3138206796024
1996-01-01	59.6054125935710
1997-01-01	59.8825104805553
1998-01-01	60.1554229828012
1999-01-01	60.4444868001426
2000-01-01	60.7609203963484
2001-01-01	61.1194552240110
2002-01-01	61.4807408929740
2003-01-01	61.8555648584896
2004-01-01	62.2464680887761
2005-01-01	62.6432421684430
2006-01-01	63.0142872558170
2007-01-01	63.4019933888303
2008-01-01	63.7872172245075
2009-01-01	64.1399083157989
2010-01-01	64.4400460194829
2011-01-01	64.6780212183546
2012-01-01	64.8651648070428
2013-01-01	65.0134222277011
2014-01-01	65.1470034533554
2015-01-01	65.2792324590458
2016-01-01	65.3633198053279
2017-01-01	65.4634400818144