Year	Percent of Total
1960-01-01	4.69634914994421
1961-01-01	4.64861301067752
1962-01-01	4.58853351197130
1963-01-01	4.52499272997512
1964-01-01	4.46836836205287
1965-01-01	4.42285761652617
1966-01-01	4.46459808850818
1967-01-01	4.51334787892346
1968-01-01	4.57163631406142
1969-01-01	4.64224744323652
1970-01-01	4.72745234774523
1971-01-01	4.87243327329765
1972-01-01	5.02798930571479
1973-01-01	5.19335305077694
1974-01-01	5.36987824465170
1975-01-01	5.55609785858093
1976-01-01	5.75453342331525
1977-01-01	5.95812473765160
1978-01-01	6.14282031945669
1979-01-01	6.27417921406156
1980-01-01	6.33594169411968
1981-01-01	6.32887465040458
1982-01-01	6.25646019446176
1983-01-01	6.16452048558036
1984-01-01	6.11193695347736
1985-01-01	6.13201691214988
1986-01-01	6.26126393558261
1987-01-01	6.45117087308272
1988-01-01	6.68640094051004
1989-01-01	6.94221456579547
1990-01-01	7.20448766373380
1991-01-01	7.49480008548629
1992-01-01	7.78564851993228
1993-01-01	8.08068232908003
1994-01-01	8.38395057180617
1995-01-01	8.69531456416028
1996-01-01	8.94652422813823
1997-01-01	9.19419343578388
1998-01-01	9.43646228710220
1999-01-01	9.66951097464229
2000-01-01	9.89119916808325
2001-01-01	10.15247385749850
2002-01-01	10.39372784207160
2003-01-01	10.61586830983930
2004-01-01	10.81929581579810
2005-01-01	11.00403247726510
2006-01-01	11.14298801102200
2007-01-01	11.26689576839620
2008-01-01	11.38108270475940
2009-01-01	11.48952705364140
2010-01-01	11.59672947677130
2011-01-01	11.75839601077600
2012-01-01	11.90678464597530
2013-01-01	12.06471526526220
2014-01-01	12.26505960303150
2015-01-01	12.52536901699990
2016-01-01	12.86701076202930
2017-01-01	13.25990322394820