Year	Percent of Total
1960-01-01	29.1801806080459
1961-01-01	29.0319113553433
1962-01-01	28.7267706838154
1963-01-01	28.2998788172691
1964-01-01	27.8214805684599
1965-01-01	27.3374333300562
1966-01-01	26.7654593865712
1967-01-01	26.2854998715117
1968-01-01	25.8494387133696
1969-01-01	25.3914866830365
1970-01-01	24.8976271748411
1971-01-01	24.6066626116261
1972-01-01	24.2292636336804
1973-01-01	23.8424871127767
1974-01-01	23.5572530118757
1975-01-01	23.4232978891794
1976-01-01	23.3955659860349
1977-01-01	23.5046486540828
1978-01-01	23.7009763736368
1979-01-01	23.8859188979951
1980-01-01	24.0037060696082
1981-01-01	24.1555890772582
1982-01-01	24.2143711732072
1983-01-01	24.2029338848207
1984-01-01	24.1695151777141
1985-01-01	24.1348442049570
1986-01-01	23.9725686704472
1987-01-01	23.8439255468608
1988-01-01	23.7035786601131
1989-01-01	23.4906028895953
1990-01-01	23.1720494060194
1991-01-01	22.8760026750559
1992-01-01	22.4487942718996
1993-01-01	21.9308215734043
1994-01-01	21.3997822782250
1995-01-01	20.8894239101972
1996-01-01	20.3416387573843
1997-01-01	19.8248219591607
1998-01-01	19.3318904442025
1999-01-01	18.8264593922598
2000-01-01	18.2982727833750
2001-01-01	17.7567099697084
2002-01-01	17.2243186301864
2003-01-01	16.7091586728931
2004-01-01	16.2399347727049
2005-01-01	15.8394426712707
2006-01-01	15.5533966516391
2007-01-01	15.3442552852834
2008-01-01	15.2000080587753
2009-01-01	15.0952844107821
2010-01-01	15.0113559185672
2011-01-01	15.0038907756044
2012-01-01	14.9651390328650
2013-01-01	14.9206274974183
2014-01-01	14.9069651222978
2015-01-01	14.9358719877639
2016-01-01	14.8975040119225
2017-01-01	14.9303788932819