Year	Percent of Total
1960-01-01	56.1764435474729
1961-01-01	55.8988494182462
1962-01-01	55.5959093705147
1963-01-01	55.2992338477220
1964-01-01	55.0715321837653
1965-01-01	54.9375405036984
1966-01-01	54.5985622233621
1967-01-01	54.3730654572770
1968-01-01	54.2348222156702
1969-01-01	54.1449345483281
1970-01-01	54.0791611043615
1971-01-01	53.8086285361416
1972-01-01	53.6009977833731
1973-01-01	53.4439487529222
1974-01-01	53.3268269079744
1975-01-01	53.2420356021767
1976-01-01	52.9709980266699
1977-01-01	52.7799364018020
1978-01-01	52.6472740247598
1979-01-01	52.5420648635571
1980-01-01	52.4424433648217
1981-01-01	52.1965755552104
1982-01-01	51.9757856140955
1983-01-01	51.7977698533129
1984-01-01	51.7265383687286
1985-01-01	51.8352333236795
1986-01-01	51.6593220285099
1987-01-01	51.5878199361668
1988-01-01	51.6342969576322
1989-01-01	51.7801573990453
1990-01-01	51.9932940180199
1991-01-01	52.0879089943197
1992-01-01	52.3251508234667
1993-01-01	52.6406725566030
1994-01-01	52.9019790002906
1995-01-01	52.9458177114631
1996-01-01	53.1192568019317
1997-01-01	53.2632398390651
1998-01-01	53.3483702081721
1999-01-01	53.4509555248859
2000-01-01	53.6710761783062
2001-01-01	53.5759371368432
2002-01-01	53.5532604625150
2003-01-01	53.6035976770672
2004-01-01	53.6627467326363
2005-01-01	53.6607966932722
2006-01-01	53.5808294118379
2007-01-01	53.5160088495877
2008-01-01	53.4663593405720
2009-01-01	53.4738036818830
2010-01-01	53.5806490422669
2011-01-01	53.6751686110177
2012-01-01	53.8268585215624
2013-01-01	54.0401713276117
2014-01-01	54.3013166126780
2015-01-01	54.5913311365557
2016-01-01	54.8490048274500
2017-01-01	55.1320757428402