Year	Percent of Total
1960-01-01	43.1019796588569
1961-01-01	43.5296108753548
1962-01-01	43.9330084622675
1963-01-01	44.2792207529192
1964-01-01	44.5197409496963
1965-01-01	44.6370511902318
1966-01-01	44.8342217062318
1967-01-01	44.8867934702236
1968-01-01	44.8382666634212
1969-01-01	44.7411266123869
1970-01-01	44.6192381841277
1971-01-01	44.6244434148171
1972-01-01	44.5727394685030
1973-01-01	44.4834971784434
1974-01-01	44.3768752492724
1975-01-01	44.2666284653512
1976-01-01	44.2154113185654
1977-01-01	44.1690750053541
1978-01-01	44.1200504234602
1979-01-01	44.0616709694501
1980-01-01	43.9983804082813
1981-01-01	44.0365406239057
1982-01-01	44.0435453630802
1983-01-01	44.0284265320382
1984-01-01	43.9975740280009
1985-01-01	43.9462115659853
1986-01-01	43.9735738108393
1987-01-01	43.9443578293371
1988-01-01	43.8479910742440
1989-01-01	43.6661061300024
1990-01-01	43.4294616614654
1991-01-01	43.1027199456784
1992-01-01	42.6823471392000
1993-01-01	42.1759922372378
1994-01-01	41.5990100591307
1995-01-01	40.9625581539549
1996-01-01	40.2232461223477
1997-01-01	39.4564670924695
1998-01-01	38.6590819971288
1999-01-01	37.8292663462141
2000-01-01	36.9702051676767
2001-01-01	36.0992536581979
2002-01-01	35.2151973479374
2003-01-01	34.3333495926413
2004-01-01	33.4900474243219
2005-01-01	32.7241660174997
2006-01-01	32.2093975167801
2007-01-01	31.7607104542116
2008-01-01	31.3962148842566
2009-01-01	31.1274916621733
2010-01-01	30.9532457345180
2011-01-01	30.9227772450269
2012-01-01	30.9819355069665
2013-01-01	31.0938984240061
2014-01-01	31.1986105241285
2015-01-01	31.2564625107828
2016-01-01	31.3105769041126
2017-01-01	31.2594097397525