Year	Percent of Total
1960-01-01	55.0646589934074
1961-01-01	54.7473132285286
1962-01-01	54.5790289355681
1963-01-01	54.5008817957377
1964-01-01	54.4430835522390
1965-01-01	54.3764830082546
1966-01-01	54.0335022567723
1967-01-01	53.7385021927901
1968-01-01	53.4891826426637
1969-01-01	53.2969586237064
1970-01-01	53.1652400391403
1971-01-01	52.8218290261061
1972-01-01	52.5757084578150
1973-01-01	52.4081500374715
1974-01-01	52.3081650257870
1975-01-01	52.2829425796999
1976-01-01	52.0109773144691
1977-01-01	51.7897556525185
1978-01-01	51.6293196403554
1979-01-01	51.5643591440248
1980-01-01	51.6405565363890
1981-01-01	51.3503035172332
1982-01-01	51.1194154817644
1983-01-01	50.9396559232026
1984-01-01	50.7653907180267
1985-01-01	50.5293620921578
1986-01-01	50.3255440610890
1987-01-01	50.2338786313999
1988-01-01	50.1780712194764
1989-01-01	50.0525531115866
1990-01-01	49.7467245386075
1991-01-01	49.7597481601985
1992-01-01	49.7833845961060
1993-01-01	49.7754337351481
1994-01-01	49.7791620567945
1995-01-01	49.8727948311595
1996-01-01	49.6783461082954
1997-01-01	49.4943504661318
1998-01-01	49.3595446013329
1999-01-01	49.2669378730092
2000-01-01	49.1820145521823
2001-01-01	49.2786169989664
2002-01-01	49.4672479061915
2003-01-01	49.7016694363211
2004-01-01	49.9602740232080
2005-01-01	50.2482689222736
2006-01-01	50.0921623035941
2007-01-01	49.9423108539902
2008-01-01	49.8364129505092
2009-01-01	49.8154803269537
2010-01-01	49.8986031640201
2011-01-01	50.3193368357761
2012-01-01	50.8831819752303
2013-01-01	51.5459309949096
2014-01-01	52.2531001568471
2015-01-01	52.9748764053550
2016-01-01	53.5989174986911
2017-01-01	54.1749144900627