Year	Percent of Total
1960-01-01	43.8471896847503
1961-01-01	43.3583462606876
1962-01-01	42.9257447754558
1963-01-01	42.4887556221889
1964-01-01	41.9501332585215
1965-01-01	41.2900976290098
1966-01-01	40.6895954257992
1967-01-01	39.9000947377487
1968-01-01	39.0110642962354
1969-01-01	38.1347273779927
1970-01-01	37.3160862130268
1971-01-01	36.0868102288022
1972-01-01	35.0150401069519
1973-01-01	33.9890111714224
1974-01-01	32.8690853819720
1975-01-01	31.5775590616087
1976-01-01	30.8784207572707
1977-01-01	29.9075638604513
1978-01-01	28.7340066219656
1979-01-01	27.5425141713905
1980-01-01	26.5142438764643
1981-01-01	25.8292469496591
1982-01-01	25.3142065368001
1983-01-01	25.0012057683960
1984-01-01	24.7851550066841
1985-01-01	24.5279725827436
1986-01-01	24.8627163016410
1987-01-01	24.9769540536607
1988-01-01	24.8530591529003
1989-01-01	24.6411718442784
1990-01-01	24.5474585270881
1991-01-01	24.0846770449692
1992-01-01	23.8044991573240
1993-01-01	23.6855897605649
1994-01-01	23.5984354628422
1995-01-01	23.4201483989841
1996-01-01	23.5625000000000
1997-01-01	23.5831061075938
1998-01-01	23.4907249332585
1999-01-01	23.3481265097466
2000-01-01	23.1792015673671
2001-01-01	22.9186850093651
2002-01-01	22.6229577227556
2003-01-01	22.2775389880124
2004-01-01	21.8823743885271
2005-01-01	21.4733432635883
2006-01-01	21.2244128847985
2007-01-01	21.0788381742739
2008-01-01	21.0028316872712
2009-01-01	20.9476309226933
2010-01-01	20.8736192939834
2011-01-01	20.5334483062722
2012-01-01	20.1048968092262
2013-01-01	19.6148739666818
2014-01-01	19.1309793342647
2015-01-01	18.7030984943598
2016-01-01	18.2413997061685
2017-01-01	17.9111567107463