Year	Percent of Total
1960-01-01	23.5103980260413
1961-01-01	23.7780837203172
1962-01-01	23.8807610028071
1963-01-01	23.8702027693630
1964-01-01	23.8409344738273
1965-01-01	23.8334343328562
1966-01-01	23.8434808030096
1967-01-01	23.8189736177047
1968-01-01	23.7666553936268
1969-01-01	23.6804025479676
1970-01-01	23.5552387932950
1971-01-01	23.3321267091945
1972-01-01	23.1148622396353
1973-01-01	22.8759559050984
1974-01-01	22.5823277268334
1975-01-01	22.2252968965325
1976-01-01	21.8657555960692
1977-01-01	21.4427135158306
1978-01-01	20.9853922215059
1979-01-01	20.5424858415707
1980-01-01	20.1417266905090
1981-01-01	19.7549296641335
1982-01-01	19.4291930776523
1983-01-01	19.1531115754081
1984-01-01	18.9001603109756
1985-01-01	18.6581601032130
1986-01-01	18.4832979504946
1987-01-01	18.3012885664458
1988-01-01	18.1314627342851
1989-01-01	18.0019771194416
1990-01-01	17.9260791737887
1991-01-01	17.8467833630246
1992-01-01	17.8297181185225
1993-01-01	17.8566875462141
1994-01-01	17.8865644753567
1995-01-01	17.8892149803093
1996-01-01	17.8739600960985
1997-01-01	17.8131414879552
1998-01-01	17.7218619872292
1999-01-01	17.6331037253441
2000-01-01	17.5658062953114
2001-01-01	17.4391577338892
2002-01-01	17.3494930238010
2003-01-01	17.2851854183767
2004-01-01	17.2220787229761
2005-01-01	17.1500668538562
2006-01-01	17.0980229231568
2007-01-01	17.0365405710595
2008-01-01	16.9748272896260
2009-01-01	16.9230471746150
2010-01-01	16.8827412373583
2011-01-01	16.9161895901447
2012-01-01	16.9275547996806
2013-01-01	16.9356137535430
2014-01-01	16.9594321714431
2015-01-01	17.0041566486002
2016-01-01	17.0312418699887
2017-01-01	17.0949475980057