Year	Percent of Total
1960-01-01	7.98820909130466
1961-01-01	8.11696439852760
1962-01-01	8.22610049398108
1963-01-01	8.32907512639387
1964-01-01	8.44584149693314
1965-01-01	8.59094968383359
1966-01-01	8.77619447718186
1967-01-01	8.99025760909154
1968-01-01	9.22486119820393
1969-01-01	9.46036579443526
1970-01-01	9.68134955133130
1971-01-01	9.86883501365521
1972-01-01	10.03439445887670
1973-01-01	10.18772040778830
1974-01-01	10.34693226565770
1975-01-01	10.52292705413090
1976-01-01	10.71201713315550
1977-01-01	10.92116741386660
1978-01-01	11.13590800692890
1979-01-01	11.33064516129030
1980-01-01	11.49410633573120
1981-01-01	11.65254737167850
1982-01-01	11.76830437341180
1983-01-01	11.86865342152270
1984-01-01	11.99294228582700
1985-01-01	12.16465751847040
1986-01-01	12.41269726474050
1987-01-01	12.69609285030250
1988-01-01	13.00803119757280
1989-01-01	13.33186042542380
1990-01-01	13.65592630484260
1991-01-01	13.94125540958440
1992-01-01	14.21644633099340
1993-01-01	14.48366563248760
1994-01-01	14.75076367531350
1995-01-01	15.02547603459600
1996-01-01	15.26709034207270
1997-01-01	15.52102027150900
1998-01-01	15.78567808567640
1999-01-01	16.05171571001760
2000-01-01	16.31111459194520
2001-01-01	16.53179556493740
2002-01-01	16.73306734760240
2003-01-01	16.91655272523520
2004-01-01	17.08810034091080
2005-01-01	17.25602687104330
2006-01-01	17.49958089428900
2007-01-01	17.74763596271730
2008-01-01	18.01850508524190
2009-01-01	18.33059177818620
2010-01-01	18.69340024582440
2011-01-01	19.06228794776260
2012-01-01	19.45933502371660
2013-01-01	19.87747720911570
2014-01-01	20.30563352626950
2015-01-01	20.73863415492850
2016-01-01	21.11980116523670
2017-01-01	21.50215121613750