Year	Percent of Total
1960-01-01	56.1534059985872
1961-01-01	55.8751085684595
1962-01-01	55.5753653001194
1963-01-01	55.3155683216851
1964-01-01	55.1984319688619
1965-01-01	55.2617382096990
1966-01-01	55.0806066243271
1967-01-01	55.0983400961256
1968-01-01	55.2593471966525
1969-01-01	55.4874480157675
1970-01-01	55.7501238219145
1971-01-01	55.6633457165372
1972-01-01	55.6193668305301
1973-01-01	55.6174324061827
1974-01-01	55.6639961155621
1975-01-01	55.7570212857606
1976-01-01	55.5111248148793
1977-01-01	55.3467512897626
1978-01-01	55.2340417639456
1979-01-01	55.1318599315516
1980-01-01	55.0039650683902
1981-01-01	54.6566243640224
1982-01-01	54.3821319424680
1983-01-01	54.1476596176361
1984-01-01	53.9406296883117
1985-01-01	53.7593167985868
1986-01-01	53.4316341532951
1987-01-01	53.2040145811108
1988-01-01	53.0454112256570
1989-01-01	52.9064653352862
1990-01-01	52.7378981356688
1991-01-01	52.5139508801632
1992-01-01	52.3525197674511
1993-01-01	52.2373268170977
1994-01-01	52.1996964327065
1995-01-01	52.2899191772306
1996-01-01	52.1457471160344
1997-01-01	52.0802500555290
1998-01-01	52.1036487376602
1999-01-01	52.2004920630537
2000-01-01	52.3482990268769
2001-01-01	52.3249611894320
2002-01-01	52.3689211691142
2003-01-01	52.4659586278960
2004-01-01	52.6034092538757
2005-01-01	52.7693756395442
2006-01-01	52.8129638752618
2007-01-01	52.9072341957943
2008-01-01	53.0394912711653
2009-01-01	53.2039997256673
2010-01-01	53.3974543665701
2011-01-01	53.5124062429487
2012-01-01	53.6795784307877
2013-01-01	53.8800245999368
2014-01-01	54.0904758956179
2015-01-01	54.2948607095560
2016-01-01	54.4420327197876
2017-01-01	54.6063685837170