Year	Percent of Total
1960-01-01	47.7722309870909
1961-01-01	48.3999845131798
1962-01-01	48.7862731445969
1963-01-01	48.9951246740222
1964-01-01	49.1291459975634
1965-01-01	49.2418341976669
1966-01-01	49.0408793756828
1967-01-01	48.7993067933723
1968-01-01	48.5197162785990
1969-01-01	48.1873959475261
1970-01-01	47.8070688267887
1971-01-01	47.7110448236542
1972-01-01	47.5621407234480
1973-01-01	47.3960960149145
1974-01-01	47.2592380191251
1975-01-01	47.1749162440251
1976-01-01	47.3358759811348
1977-01-01	47.4936069360306
1978-01-01	47.6560585795398
1979-01-01	47.8274276912944
1980-01-01	48.0100631896413
1981-01-01	48.4211383863728
1982-01-01	48.7712872372945
1983-01-01	49.0692352352487
1984-01-01	49.3362355671784
1985-01-01	49.5867474212461
1986-01-01	49.8356657456874
1987-01-01	50.0541507585042
1988-01-01	50.1819654947619
1989-01-01	50.0251384833873
1990-01-01	49.3746646879860
1991-01-01	48.8830091896221
1992-01-01	47.8551970194503
1993-01-01	46.2881447970122
1994-01-01	44.5286044600460
1995-01-01	43.1417063000858
1996-01-01	42.8170902254852
1997-01-01	42.9726440432345
1998-01-01	43.5295949057008
1999-01-01	44.0822552799932
2000-01-01	44.2899893006257
2001-01-01	44.0077239601479
2002-01-01	43.4704649197155
2003-01-01	42.7573854774913
2004-01-01	42.1209175593229
2005-01-01	41.7361499198987
2006-01-01	41.5209665261150
2007-01-01	41.5255643826737
2008-01-01	41.6675688278603
2009-01-01	41.7780261602017
2010-01-01	41.7630914968729
2011-01-01	41.7374511830512
2012-01-01	41.5854030080862
2013-01-01	41.3423820425044
2014-01-01	41.0716736370658
2015-01-01	40.8006051479365
2016-01-01	40.4706168437227
2017-01-01	40.1371366469024