Year	Percent of Total
1960-01-01	54.6167899414103
1961-01-01	54.3407580250690
1962-01-01	54.0892631247899
1963-01-01	53.8642426795892
1964-01-01	53.6947280701016
1965-01-01	53.5876445668011
1966-01-01	53.2039996398648
1967-01-01	52.9390920318970
1968-01-01	52.7551885193221
1969-01-01	52.6073439962164
1970-01-01	52.4656764703919
1971-01-01	52.3501014173610
1972-01-01	52.3074257649224
1973-01-01	52.3109609099777
1974-01-01	52.3403454910141
1975-01-01	52.3758025327266
1976-01-01	52.1815888008953
1977-01-01	52.0492002293336
1978-01-01	51.9676996074567
1979-01-01	51.9368804651311
1980-01-01	51.9527109514178
1981-01-01	51.7739553190844
1982-01-01	51.7149976565799
1983-01-01	51.7409645202434
1984-01-01	51.8189446324084
1985-01-01	51.9316202461263
1986-01-01	51.8790817594322
1987-01-01	51.8750911439936
1988-01-01	51.9272145416858
1989-01-01	52.0474408710084
1990-01-01	52.2315983838606
1991-01-01	52.3360960905768
1992-01-01	52.5190003904120
1993-01-01	52.7571160290840
1994-01-01	53.0189239109203
1995-01-01	53.2829303986983
1996-01-01	53.3028227807354
1997-01-01	53.3435741816676
1998-01-01	53.4098286183960
1999-01-01	53.5121737216885
2000-01-01	53.6538175841026
2001-01-01	53.4523283595123
2002-01-01	53.3067856957155
2003-01-01	53.2102104403696
2004-01-01	53.1463565032450
2005-01-01	53.1055415041952
2006-01-01	53.1063532133458
2007-01-01	53.1297042152650
2008-01-01	53.1855238792355
2009-01-01	53.2822380969531
2010-01-01	53.4136816857684
2011-01-01	53.5680612746085
2012-01-01	53.7575910062855
2013-01-01	53.9714176872294
2014-01-01	54.1939386676786
2015-01-01	54.4124120365899
2016-01-01	54.5129015675653
2017-01-01	54.6344210168864