Year	Percent of Total
1960-01-01	43.3581232961882
1961-01-01	43.5038079956609
1962-01-01	43.3930618657382
1963-01-01	43.2106371983941
1964-01-01	43.1592351951517
1965-01-01	43.2913198159408
1966-01-01	43.7346377354191
1967-01-01	44.1958339992542
1968-01-01	44.6562059489399
1969-01-01	45.0699526976989
1970-01-01	45.4042678458464
1971-01-01	45.8322509033370
1972-01-01	46.1372360844530
1973-01-01	46.3635027916544
1974-01-01	46.6076293613931
1975-01-01	46.9344241088753
1976-01-01	47.3555255153768
1977-01-01	47.5556708795981
1978-01-01	47.5201942806680
1979-01-01	47.1675320231489
1980-01-01	46.4659014932026
1981-01-01	46.3723238837458
1982-01-01	46.0161808181773
1983-01-01	45.5188140232909
1984-01-01	45.1458929059621
1985-01-01	45.0935474245383
1986-01-01	44.9171473784062
1987-01-01	45.0659759753635
1988-01-01	45.3312766186704
1989-01-01	45.3760126555340
1990-01-01	45.0111619619308
1991-01-01	45.0671012649050
1992-01-01	44.7307065721059
1993-01-01	44.1329355936588
1994-01-01	43.5505795625082
1995-01-01	43.1630995513874
1996-01-01	42.6006941315743
1997-01-01	42.2429431442175
1998-01-01	41.9751635292942
1999-01-01	41.5856900238395
2000-01-01	40.9756906508506
2001-01-01	40.5767075968561
2002-01-01	39.9830613182958
2003-01-01	39.2626035604358
2004-01-01	38.5389853026655
2005-01-01	37.8750699006963
2006-01-01	37.2488093563491
2007-01-01	36.6302529521795
2008-01-01	36.0257323187522
2009-01-01	35.4294727785479
2010-01-01	34.8400861896784
2011-01-01	34.2312431504832
2012-01-01	33.6638730800002
2013-01-01	33.1193235551273
2014-01-01	32.5703491915927
2015-01-01	32.0074961128471
2016-01-01	31.5683521642562
2017-01-01	31.0866941488111