Year	Percent of Total
1960-01-01	53.6699193890539
1961-01-01	54.0567841552726
1962-01-01	54.3832814584260
1963-01-01	54.7102919128671
1964-01-01	55.1199326693786
1965-01-01	55.6311018131102
1966-01-01	56.0755436195097
1967-01-01	56.7031263457067
1968-01-01	57.4144486692015
1969-01-01	58.0867077614685
1970-01-01	58.6797148807206
1971-01-01	59.5524899057874
1972-01-01	60.2489973262032
1973-01-01	60.8900619159072
1974-01-01	61.6392413428496
1975-01-01	62.5665628039633
1976-01-01	63.0789291255405
1977-01-01	63.8505118775470
1978-01-01	64.8253830923581
1979-01-01	65.8102700900300
1980-01-01	66.6350505857295
1981-01-01	67.1851007974640
1982-01-01	67.5784497514060
1983-01-01	67.8043761354319
1984-01-01	67.9451269972627
1985-01-01	68.1544124646971
1986-01-01	67.7558904284528
1987-01-01	67.5674801481410
1988-01-01	67.6140735768431
1989-01-01	67.7497050727487
1990-01-01	67.7967465285041
1991-01-01	68.5231035870137
1992-01-01	69.0217630248406
1993-01-01	69.2982456140351
1994-01-01	69.4719687092568
1995-01-01	69.6678452268313
1996-01-01	69.4507211538461
1997-01-01	69.3262805584487
1998-01-01	69.2794206950285
1999-01-01	69.2612774563227
2000-01-01	69.2404213399668
2001-01-01	69.3233438825378
2002-01-01	69.4216355061479
2003-01-01	69.5548202892277
2004-01-01	69.7347498911249
2005-01-01	69.9353200507843
2006-01-01	69.8567914947636
2007-01-01	69.6917605216360
2008-01-01	69.4483636399515
2009-01-01	69.1610893714331
2010-01-01	68.8380922405060
2011-01-01	68.8828353894545
2012-01-01	68.9764762081168
2013-01-01	69.0900985589270
2014-01-01	69.1651813671179
2015-01-01	69.1597742018957
2016-01-01	69.1524679933602
2017-01-01	69.0036479708162