Year	Percent of Total
1960-01-01	2.48289092619579
1961-01-01	2.58486958403983
1962-01-01	2.69097376611827
1963-01-01	2.80095246494400
1964-01-01	2.92993407209987
1965-01-01	3.07880055788006
1966-01-01	3.23486095469116
1967-01-01	3.39677891654466
1968-01-01	3.57448703456308
1969-01-01	3.77856486053877
1970-01-01	4.00419890625265
1971-01-01	4.36069986541050
1972-01-01	4.73596256684492
1973-01-01	5.12092691267035
1974-01-01	5.49167327517843
1975-01-01	5.85587813442801
1976-01-01	6.04265011718879
1977-01-01	6.24192426200179
1978-01-01	6.44061028567626
1979-01-01	6.64721573857953
1980-01-01	6.85070553780618
1981-01-01	6.98565225287698
1982-01-01	7.10734371179395
1983-01-01	7.19441809617209
1984-01-01	7.26971799605322
1985-01-01	7.31761495255926
1986-01-01	7.38139326990613
1987-01-01	7.45556579819837
1988-01-01	7.53286727025655
1989-01-01	7.60912308297287
1990-01-01	7.65579494440779
1991-01-01	7.39221936801708
1992-01-01	7.17373781783542
1993-01-01	7.01616462539998
1994-01-01	6.92959582790091
1995-01-01	6.91200637418455
1996-01-01	6.98677884615385
1997-01-01	7.09061333395747
1998-01-01	7.22985437171305
1999-01-01	7.39059603393068
2000-01-01	7.58037709266618
2001-01-01	7.75797110809705
2002-01-01	7.95540677109651
2003-01-01	8.16764072275993
2004-01-01	8.38287572034799
2005-01-01	8.59133668562746
2006-01-01	8.91879562043796
2007-01-01	9.22940130409010
2008-01-01	9.54880467277732
2009-01-01	9.89127970587366
2010-01-01	10.28828846551060
2011-01-01	10.58371630427330
2012-01-01	10.91862698265690
2013-01-01	11.29502747439120
2014-01-01	11.70383929861750
2015-01-01	12.13712730374450
2016-01-01	12.60613230047130
2017-01-01	13.08519531843750