Year	Percent of Total
1960-01-01	28.4051060566187
1961-01-01	28.3789463605973
1962-01-01	28.2530488312142
1963-01-01	28.0634517696742
1964-01-01	27.8648770261050
1965-01-01	27.6792201160706
1966-01-01	27.4975847378707
1967-01-01	27.3125040484154
1968-01-01	27.1235792956750
1969-01-01	26.9139637754556
1970-01-01	26.6909041918574
1971-01-01	26.3861375788222
1972-01-01	26.0833029784050
1973-01-01	25.7724783350700
1974-01-01	25.4313080658861
1975-01-01	25.0554518308569
1976-01-01	24.7264868312252
1977-01-01	24.3423049006904
1978-01-01	23.9273216578993
1979-01-01	23.5188496706106
1980-01-01	23.1383544161105
1981-01-01	22.7552737820176
1982-01-01	22.4211195353407
1983-01-01	22.1196882351731
1984-01-01	21.8207383221104
1985-01-01	21.5114097912701
1986-01-01	21.2733077445480
1987-01-01	21.0056128120284
1988-01-01	20.7265370386517
1989-01-01	20.4662551384363
1990-01-01	20.2416716834957
1991-01-01	20.0591717682070
1992-01-01	19.9087460486974
1993-01-01	19.7731089379827
1994-01-01	19.6236272993261
1995-01-01	19.4463972192886
1996-01-01	19.2948009721547
1997-01-01	19.1069294618299
1998-01-01	18.8959451081430
1999-01-01	18.6883516425744
2000-01-01	18.4958403285025
2001-01-01	18.2905108679176
2002-01-01	18.1041717864354
2003-01-01	17.9235092152936
2004-01-01	17.7346043003217
2005-01-01	17.5351180273076
2006-01-01	17.4228602734976
2007-01-01	17.3001290592951
2008-01-01	17.1708624937315
2009-01-01	17.0404205309721
2010-01-01	16.9097206346773
2011-01-01	16.8150748172336
2012-01-01	16.7083108120921
2013-01-01	16.5948111908738
2014-01-01	16.5126685685148