Year	Percent of Total
1960-01-01	3.77802936235483
1961-01-01	3.68784098411926
1962-01-01	3.60579106893618
1963-01-01	3.54032340398797
1964-01-01	3.49219883618304
1965-01-01	3.45009781941251
1966-01-01	3.41062815134662
1967-01-01	3.38184510743141
1968-01-01	3.36953986395759
1969-01-01	3.37112171837709
1970-01-01	3.38462628576827
1971-01-01	3.46709765735090
1972-01-01	3.52341162512160
1973-01-01	3.57158600017632
1974-01-01	3.62454686411056
1975-01-01	3.68272254635169
1976-01-01	3.76667945381593
1977-01-01	3.86787140240778
1978-01-01	3.98038836204116
1979-01-01	4.07897802283141
1980-01-01	4.15121925748003
1981-01-01	4.20342067633568
1982-01-01	4.21700147542844
1983-01-01	4.20717004089934
1984-01-01	4.19842184205378
1985-01-01	4.20091440940487
1986-01-01	4.20229915820199
1987-01-01	4.22197844638095
1988-01-01	4.25238004838860
1989-01-01	4.28312202947004
1990-01-01	4.31699020036202
1991-01-01	4.38157753642060
1992-01-01	4.44212314097410
1993-01-01	4.50094960632825
1994-01-01	4.56622990630494
1995-01-01	4.64715331072640
1996-01-01	4.76796222558935
1997-01-01	4.89842143778095
1998-01-01	5.04206026339378
1999-01-01	5.19293393102885
2000-01-01	5.35130417268119
2001-01-01	5.52987942665809
2002-01-01	5.70486840019796
2003-01-01	5.86959138041337
2004-01-01	6.03331204306009
2005-01-01	6.21839398145476
2006-01-01	6.36393413334127
2007-01-01	6.51100698745063
2008-01-01	6.65345478323716
2009-01-01	6.79853236242307
2010-01-01	6.95143446257538
2011-01-01	7.17111149909430
2012-01-01	7.42529681028064
2013-01-01	7.70172834269961
2014-01-01	7.99593896940882
2015-01-01	8.30606093506842
2016-01-01	8.64525396695567
2017-01-01	8.99582912831564