Year	Percent of Total
1960-01-01	13.1666971303235
1961-01-01	13.2166052228734
1962-01-01	13.2939160393694
1963-01-01	13.3869177139305
1964-01-01	13.4794722825275
1965-01-01	13.5727640332188
1966-01-01	13.6345255405371
1967-01-01	13.7060115429797
1968-01-01	13.7720465609892
1969-01-01	13.8415630313740
1970-01-01	13.9203115588670
1971-01-01	14.0442600050648
1972-01-01	14.1416020839064
1973-01-01	14.2232912407296
1974-01-01	14.3011728011967
1975-01-01	14.3788316259937
1976-01-01	14.6018187262612
1977-01-01	14.7881399243610
1978-01-01	14.9203234162807
1979-01-01	14.9868433417912
1980-01-01	15.0048357408043
1981-01-01	15.0370984873741
1982-01-01	15.0185799244493
1983-01-01	14.9699594376163
1984-01-01	14.9041546812832
1985-01-01	14.8406672246801
1986-01-01	14.8177179619907
1987-01-01	14.7853945405073
1988-01-01	14.7387236136540
1989-01-01	14.6771303662295
1990-01-01	14.5964697769974
1991-01-01	14.6155910940326
1992-01-01	14.6220247718933
1993-01-01	14.6101008969395
1994-01-01	14.5762428164928
1995-01-01	14.5252211099232
1996-01-01	14.5233344150688
1997-01-01	14.4837525306249
1998-01-01	14.4193467011202
1999-01-01	14.3655162607406
2000-01-01	14.3244242729871
2001-01-01	14.4746416721743
2002-01-01	14.6089157792195
2003-01-01	14.7068496033886
2004-01-01	14.7803094600770
2005-01-01	14.8858672404630
2006-01-01	15.0928827431778
2007-01-01	15.3150217553813
2008-01-01	15.5158299541188
2009-01-01	15.6812922832481
2010-01-01	15.8446180936327
2011-01-01	16.0806744051291
2012-01-01	16.3481203287101
2013-01-01	16.6432359107165
2014-01-01	16.9578263350699
2015-01-01	17.2932009428547
2016-01-01	17.6472733239740
2017-01-01	18.0142032737699