Year	Percent of Total
1960-01-01	63.5161273091520
1961-01-01	63.2441209103489
1962-01-01	63.0834764633281
1963-01-01	63.0137862568115
1964-01-01	62.9879902518668
1965-01-01	62.9813571558894
1966-01-01	62.9373081581724
1967-01-01	62.9390486451009
1968-01-01	62.9768900417420
1969-01-01	63.0402413075883
1970-01-01	63.1199148712835
1971-01-01	63.2204482380788
1972-01-01	63.3260750017390
1973-01-01	63.4395993130900
1974-01-01	63.5694782811008
1975-01-01	63.7185742180165
1976-01-01	63.7728132221279
1977-01-01	63.8632087892434
1978-01-01	63.9974221878323
1979-01-01	64.1865883243052
1980-01-01	64.4328846799846
1981-01-01	64.6821822906844
1982-01-01	64.9789297407601
1983-01-01	65.2830891195145
1984-01-01	65.5473957338938
1985-01-01	65.7443125207183
1986-01-01	65.7895728939670
1987-01-01	65.7954615185044
1988-01-01	65.7769010539674
1989-01-01	65.7564013693649
1990-01-01	65.7506652150330
1991-01-01	65.6646253155761
1992-01-01	65.6194825734014
1993-01-01	65.6185970574358
1994-01-01	65.6658790946359
1995-01-01	65.7658375339224
1996-01-01	65.9281251387106
1997-01-01	66.1232780108586
1998-01-01	66.3438927668185
1999-01-01	66.5765885993740
2000-01-01	66.8022584693147
2001-01-01	66.9467181396762
2002-01-01	67.0868915114930
2003-01-01	67.2318966658145
2004-01-01	67.3928691877704
2005-01-01	67.5727187589531
2006-01-01	67.6757163533574
2007-01-01	67.7974110080150
2008-01-01	67.9005283010617
2009-01-01	67.9456232755581
2010-01-01	67.9097398109199
2011-01-01	67.7403095020977
2012-01-01	67.5193965897321
2013-01-01	67.2531055926260
2014-01-01	66.9577750450476
2015-01-01	66.6489327159236
2016-01-01	66.3193561799580
2017-01-01	65.9872275928569