Year	Percent of Total
1960-01-01	3.93907884274268
1961-01-01	3.90672461329969
1962-01-01	3.85741096563743
1963-01-01	3.80760023937762
1964-01-01	3.76297931485569
1965-01-01	3.72662924090798
1966-01-01	3.67046852286705
1967-01-01	3.62508222660764
1968-01-01	3.59728698601102
1969-01-01	3.58098873460409
1970-01-01	3.57068442619788
1971-01-01	3.55716664456331
1972-01-01	3.53691412161354
1973-01-01	3.51777059773829
1974-01-01	3.51430284509603
1975-01-01	3.52258599254041
1976-01-01	3.43054498763553
1977-01-01	3.32431210770543
1978-01-01	3.19766960724275
1979-01-01	3.04440039220702
1980-01-01	2.86054581359017
1981-01-01	2.85878501636804
1982-01-01	2.85259644492742
1983-01-01	2.83874495606592
1984-01-01	2.82687293506303
1985-01-01	2.82301168757127
1986-01-01	2.80250419964325
1987-01-01	2.77836227285352
1988-01-01	2.74689312683569
1989-01-01	2.70243405933666
1990-01-01	2.64273431613115
1991-01-01	2.63525541359652
1992-01-01	2.62736208904122
1993-01-01	2.62430301933267
1994-01-01	2.63258785942492
1995-01-01	2.65585883873052
1996-01-01	2.59863012349893
1997-01-01	2.54488235407226
1998-01-01	2.49606856670280
1999-01-01	2.44874942152509
2000-01-01	2.39856440233945
2001-01-01	2.51854508889588
2002-01-01	2.63184448217905
2003-01-01	2.73947406399180
2004-01-01	2.85072165063153
2005-01-01	2.97323350440083
2006-01-01	3.09844699527346
2007-01-01	3.20783003969440
2008-01-01	3.29437946273190
2009-01-01	3.35876510011152
2010-01-01	3.40218493189455
2011-01-01	3.49430094946106
2012-01-01	3.60026816894644
2013-01-01	3.72896311705725
2014-01-01	3.89187377339059
2015-01-01	4.09515689439625
2016-01-01	4.32447376629269
2017-01-01	4.59065493810314