Year	Percent of Total
1960-01-01	56.9042350742334
1961-01-01	56.5771985090561
1962-01-01	56.2788123763326
1963-01-01	56.0390641524857
1964-01-01	55.9257938947830
1965-01-01	55.9639930724413
1966-01-01	55.5586291282305
1967-01-01	55.3530993223335
1968-01-01	55.2928599415136
1969-01-01	55.3026472119687
1970-01-01	55.3385291252630
1971-01-01	54.9468031426761
1972-01-01	54.6625613383613
1973-01-01	54.4563805397760
1974-01-01	54.3148709838093
1975-01-01	54.2329409506967
1976-01-01	53.7258292804679
1977-01-01	53.3415837343448
1978-01-01	53.0543915904671
1979-01-01	52.8404119323593
1980-01-01	52.6866941433763
1981-01-01	52.2132539928173
1982-01-01	51.8443197680022
1983-01-01	51.5674380741762
1984-01-01	51.3812464199451
1985-01-01	51.2875373999810
1986-01-01	50.7430519345673
1987-01-01	50.3174735781614
1988-01-01	49.9882895507588
1989-01-01	49.7230228757796
1990-01-01	49.5018066934839
1991-01-01	49.4258316137945
1992-01-01	49.4158777203608
1993-01-01	49.4595447660484
1994-01-01	49.5579407882814
1995-01-01	49.7115920224479
1996-01-01	49.6818037478657
1997-01-01	49.7468384217113
1998-01-01	49.8708726224817
1999-01-01	50.0104513217382
2000-01-01	50.1405765480242
2001-01-01	50.1255793500866
2002-01-01	50.1306176882770
2003-01-01	50.1475702716373
2004-01-01	50.1757598871392
2005-01-01	50.2125713242756
2006-01-01	50.0330307617775
2007-01-01	49.9045307388938
2008-01-01	49.8191002315992
2009-01-01	49.7774806821877
2010-01-01	49.7845285781142
2011-01-01	49.5892507227178
2012-01-01	49.4856581662519
2013-01-01	49.4544362609175
2014-01-01	49.4743629695159
2015-01-01	49.5364326746682
2016-01-01	49.6376321719391
2017-01-01	49.7753691892667