Year	Percent of Total
1960-01-01	3.67197730967430
1961-01-01	3.68736207400670
1962-01-01	3.65650833192524
1963-01-01	3.59656644499204
1964-01-01	3.52797925960746
1965-01-01	3.45886072786793
1966-01-01	3.51380667226230
1967-01-01	3.57382979061624
1968-01-01	3.63269528855880
1969-01-01	3.68217970756264
1970-01-01	3.72084731954893
1971-01-01	3.77830678625796
1972-01-01	3.83044608903480
1973-01-01	3.87946269818661
1974-01-01	3.92981608040808
1975-01-01	3.98465381669857
1976-01-01	4.07980418788561
1977-01-01	4.17498448716711
1978-01-01	4.27069231547273
1979-01-01	4.36552566036093
1980-01-01	4.45787700709057
1981-01-01	4.57357891817386
1982-01-01	4.67845456906491
1983-01-01	4.77306807238999
1984-01-01	4.85633430292005
1985-01-01	4.92800118373685
1986-01-01	4.99274797736300
1987-01-01	5.04473698457087
1988-01-01	5.09043503746099
1989-01-01	5.13990900456726
1990-01-01	5.20102668820062
1991-01-01	5.26730747564750
1992-01-01	5.35100812027883
1993-01-01	5.44694578989759
1994-01-01	5.54711789119769
1995-01-01	5.64841924162813
1996-01-01	5.79355557728288
1997-01-01	5.92449220532600
1998-01-01	6.04781915156060
1999-01-01	6.17212979938678
2000-01-01	6.30007266461134
2001-01-01	6.43482799894478
2002-01-01	6.56763711409101
2003-01-01	6.69594671276478
2004-01-01	6.81274075526642
2005-01-01	6.91687960333795
2006-01-01	7.03096177343817
2007-01-01	7.13750664601447
2008-01-01	7.24206832349447
2009-01-01	7.35306859354538
2010-01-01	7.47790560007812
2011-01-01	7.62961817276539
2012-01-01	7.78578123704501
2013-01-01	7.96306441521389
2014-01-01	8.18518865004481
2015-01-01	8.46497339629843
2016-01-01	8.80839118236285
2017-01-01	9.20369675093632