Year	Percent of Total
1960-01-01	52.5731395748902
1961-01-01	52.4579712072060
1962-01-01	52.5647526621515
1963-01-01	52.7820691414879
1964-01-01	52.9627339237834
1965-01-01	53.0434454808259
1966-01-01	52.7776468426627
1967-01-01	52.4899431136284
1968-01-01	52.2065596650384
1969-01-01	51.9882866061953
1970-01-01	51.8639805218516
1971-01-01	51.5231343562918
1972-01-01	51.3075123312365
1973-01-01	51.1798420633428
1974-01-01	51.0971753298158
1975-01-01	51.0387491856875
1976-01-01	50.7785847263967
1977-01-01	50.5905340759441
1978-01-01	50.4601724344287
1979-01-01	50.3848266350747
1980-01-01	50.3650772016589
1981-01-01	50.1304213355872
1982-01-01	50.0128923770274
1983-01-01	49.9730685544899
1984-01-01	49.9516526274636
1985-01-01	49.9054721849148
1986-01-01	50.1496399160427
1987-01-01	50.4070212003730
1988-01-01	50.7000805262515
1989-01-01	51.0999573266587
1990-01-01	51.6637416499807
1991-01-01	51.3768736996498
1992-01-01	51.2320553619391
1993-01-01	51.1745303359818
1994-01-01	51.0967465879267
1995-01-01	50.9179149483787
1996-01-01	50.7328491227661
1997-01-01	50.5509608969952
1998-01-01	50.3823258174133
1999-01-01	50.2833755087214
2000-01-01	50.2887350859322
2001-01-01	50.1739803210759
2002-01-01	50.1794408072577
2003-01-01	50.2658777028225
2004-01-01	50.3708887587746
2005-01-01	50.4583805576673
2006-01-01	50.5270952342727
2007-01-01	50.5724635319969
2008-01-01	50.6187972252434
2009-01-01	50.7147797813356
2010-01-01	50.8859606931980
2011-01-01	51.0408560024951
2012-01-01	51.3201681896442
2013-01-01	51.6710505130949
2014-01-01	52.0222173296155
2015-01-01	52.3428058906746
2016-01-01	52.7276480903404
2017-01-01	53.0315586251693