Year	Percent of Total
1960-01-01	58.0629151660664
1961-01-01	57.3328109385548
1962-01-01	56.7276158128823
1963-01-01	56.2725542416691
1964-01-01	55.9810352331757
1965-01-01	55.8729223596635
1966-01-01	55.7709598150584
1967-01-01	55.8999963952279
1968-01-01	56.2121011302514
1969-01-01	56.6141520008703
1970-01-01	57.0450822410625
1971-01-01	57.6639421464096
1972-01-01	58.1687643370890
1973-01-01	58.6202938701088
1974-01-01	59.1251309707253
1975-01-01	59.7248095922519
1976-01-01	60.0729717322844
1977-01-01	60.5161622758136
1978-01-01	60.9720502600178
1979-01-01	61.3296463055823
1980-01-01	61.5577910180332
1981-01-01	61.8721825487789
1982-01-01	62.0743510006694
1983-01-01	62.1838756529474
1984-01-01	62.2656135844529
1985-01-01	62.3611912191676
1986-01-01	62.4629153091161
1987-01-01	62.5508429088522
1988-01-01	62.6168359801657
1989-01-01	62.6625604575976
1990-01-01	62.7167484328237
1991-01-01	62.5815318085828
1992-01-01	62.5606717216246
1993-01-01	62.6440562003665
1994-01-01	62.8245824215349
1995-01-01	63.1017447132378
1996-01-01	63.5514032278485
1997-01-01	64.0703625625668
1998-01-01	64.6202688369480
1999-01-01	65.1465087968316
2000-01-01	65.6021509211141
2001-01-01	66.1293828292621
2002-01-01	66.5476184565439
2003-01-01	66.9304718747795
2004-01-01	67.3501272202448
2005-01-01	67.8217171015562
2006-01-01	68.1315448527649
2007-01-01	68.4966658470819
2008-01-01	68.8525143401960
2009-01-01	69.0920006181351
2010-01-01	69.1386157282016
2011-01-01	68.7714162829226
2012-01-01	68.2915770821880
2013-01-01	67.7158015365261
2014-01-01	67.0944206236824
2015-01-01	66.4701576053790
2016-01-01	65.7571080651840
2017-01-01	65.0806429773212