Year	Percent of Total
1960-01-01	12.1517244383423
1961-01-01	12.3380745314888
1962-01-01	12.5298019389302
1963-01-01	12.7216175866924
1964-01-01	12.9075420911893
1965-01-01	13.0871912695112
1966-01-01	13.3024493215673
1967-01-01	13.4972275211699
1968-01-01	13.6719967621824
1969-01-01	13.8289497504194
1970-01-01	13.9706840083185
1971-01-01	14.1744080399028
1972-01-01	14.3485320171157
1973-01-01	14.4978779595021
1974-01-01	14.6246995590254
1975-01-01	14.7287877262350
1976-01-01	14.9373183178769
1977-01-01	15.1212925792921
1978-01-01	15.2533922479722
1979-01-01	15.2863446069801
1980-01-01	15.1954097847078
1981-01-01	15.0686704066388
1982-01-01	14.8126570519697
1983-01-01	14.5049481119680
1984-01-01	14.2579758660538
1985-01-01	14.1362529199456
1986-01-01	14.1863770168960
1987-01-01	14.3525393253250
1988-01-01	14.5800538985016
1989-01-01	14.7856938047286
1990-01-01	14.9214734587191
1991-01-01	15.0803433709852
1992-01-01	15.1732622409105
1993-01-01	15.2109974473162
1994-01-01	15.2131144405539
1995-01-01	15.1898575753734
1996-01-01	15.2452717139218
1997-01-01	15.2779029577949
1998-01-01	15.3033745592926
1999-01-01	15.3368732993811
2000-01-01	15.3899061080573
2001-01-01	15.5200556994364
2002-01-01	15.6503383403742
2003-01-01	15.7943539095375
2004-01-01	15.9729846333216
2005-01-01	16.1973187620023
2006-01-01	16.4900023959728
2007-01-01	16.8231413163698
2008-01-01	17.1739170323320
2009-01-01	17.5056552909318
2010-01-01	17.7983837951930
2011-01-01	18.0526306333057
2012-01-01	18.2727822608103
2013-01-01	18.4698445355688
2014-01-01	18.6564572662344
2015-01-01	18.8404841901230
2016-01-01	19.0274556058978
2017-01-01	19.2015342535756