Year	Percent of Total
1960-01-01	43.8591923002575
1961-01-01	44.0242152120545
1962-01-01	44.1554326319703
1963-01-01	44.2546675352330
1964-01-01	44.3183919465696
1965-01-01	44.3418888718160
1966-01-01	44.3882570889139
1967-01-01	44.3789958236446
1968-01-01	44.3203497421335
1969-01-01	44.2197281505528
1970-01-01	44.0805266112859
1971-01-01	43.9329799790802
1972-01-01	43.7499144812213
1973-01-01	43.5267738329696
1974-01-01	43.2530973513828
1975-01-01	42.9251577894860
1976-01-01	42.6088767051103
1977-01-01	42.2261397580922
1978-01-01	41.7965365093937
1979-01-01	41.3445970749549
1980-01-01	40.8816331729151
1981-01-01	40.4003326645493
1982-01-01	39.9187209838349
1983-01-01	39.4312466098224
1984-01-01	38.9285153166984
1985-01-01	38.4101391625017
1986-01-01	37.9018713958637
1987-01-01	37.3909345167129
1988-01-01	36.8802820885428
1989-01-01	36.3743448518717
1990-01-01	35.8762756428649
1991-01-01	35.4189414076913
1992-01-01	34.9508427347945
1993-01-01	34.4873298438876
1994-01-01	34.0491687787308
1995-01-01	33.6466367123768
1996-01-01	33.2642908025622
1997-01-01	32.9303233668811
1998-01-01	32.6241069000470
1999-01-01	32.3137442586271
2000-01-01	31.9832679227824
2001-01-01	31.7087766904318
2002-01-01	31.3907213270398
2003-01-01	31.0526633956277
2004-01-01	30.7293286733520
2005-01-01	30.4357799886803
2006-01-01	30.1448006356310
2007-01-01	29.8913054493201
2008-01-01	29.6553618779911
2009-01-01	29.4096611568747
2010-01-01	29.1436261638736
2011-01-01	28.9143212842610
2012-01-01	28.6645049560846
2013-01-01	28.4000466853651
2014-01-01	28.1310435027175
2015-01-01	27.8607867634406
2016-01-01	27.6356746045419
2017-01-01	27.3880242141987