Year	Percent of Total
1960-01-01	11.7609912369000
1961-01-01	11.8565008826702
1962-01-01	11.9436122394239
1963-01-01	12.0271035096090
1964-01-01	12.1103859468471
1965-01-01	12.1998654699445
1966-01-01	12.3674367308269
1967-01-01	12.5405982115523
1968-01-01	12.7121209420019
1969-01-01	12.8762366374974
1970-01-01	13.0329980613800
1971-01-01	13.2709445930147
1972-01-01	13.4878515345344
1973-01-01	13.6887336059485
1974-01-01	13.8786172483173
1975-01-01	14.0594489637585
1976-01-01	14.3052946175917
1977-01-01	14.5309784469168
1978-01-01	14.7274952477764
1979-01-01	14.8758488992071
1980-01-01	14.9658880512428
1981-01-01	15.0744003049951
1982-01-01	15.1123609676241
1983-01-01	15.1119837882162
1984-01-01	15.1194477885432
1985-01-01	15.1608634209417
1986-01-01	15.2842351683486
1987-01-01	15.4346944855939
1988-01-01	15.5871123194523
1989-01-01	15.7057605440372
1990-01-01	15.7740933280015
1991-01-01	15.8707931033936
1992-01-01	15.9190547804732
1993-01-01	15.9303185595719
1994-01-01	15.9209189581644
1995-01-01	15.9019040927384
1996-01-01	15.9173368454510
1997-01-01	15.9176359550098
1998-01-01	15.9101321449858
1999-01-01	15.9000821288294
2000-01-01	15.8919545991942
2001-01-01	15.9290205471936
2002-01-01	15.9615840232262
2003-01-01	15.9917917056435
2004-01-01	16.0191979417317
2005-01-01	16.0450867863942
2006-01-01	16.1246025491490
2007-01-01	16.1910576399837
2008-01-01	16.2706441166900
2009-01-01	16.3999002783797
2010-01-01	16.5980398043226
2011-01-01	16.8576582649607
2012-01-01	17.1817374323214
2013-01-01	17.5336716835463
2014-01-01	17.8568768773739
2015-01-01	18.1215155172066
2016-01-01	18.3504114255463
2017-01-01	18.5172189514651