Year	Percent of Total
1960-01-01	27.6615886305437
1961-01-01	27.3802768205101
1962-01-01	27.0851277835387
1963-01-01	26.7565911472032
1964-01-01	26.3829175912630
1965-01-01	25.9696925435458
1966-01-01	25.6838894632265
1967-01-01	25.2651335401837
1968-01-01	24.7994360103059
1969-01-01	24.4003509376616
1970-01-01	24.1239568490537
1971-01-01	23.8712712475772
1972-01-01	23.7751589256479
1973-01-01	23.7754075054811
1974-01-01	23.7762201297362
1975-01-01	23.7322702615540
1976-01-01	23.7223757494753
1977-01-01	23.6550107212042
1978-01-01	23.5592387817657
1979-01-01	23.4672340547441
1980-01-01	23.3850281915007
1981-01-01	23.3030690247996
1982-01-01	23.1542550023821
1983-01-01	22.9565527110428
1984-01-01	22.7280848734284
1985-01-01	22.4750981294357
1986-01-01	22.1590043594173
1987-01-01	21.8711524348454
1988-01-01	21.5681410525512
1989-01-01	21.1953482304974
1990-01-01	20.7305932431887
1991-01-01	20.3392725874602
1992-01-01	19.8530848980210
1993-01-01	19.3019380557866
1994-01-01	18.7463263057305
1995-01-01	18.2252625193827
1996-01-01	17.6473575268642
1997-01-01	17.1409312585043
1998-01-01	16.6878775196481
1999-01-01	16.2489601763903
2000-01-01	15.8056906239329
2001-01-01	15.4089146321898
2002-01-01	14.9883516474673
2003-01-01	14.5795929038470
2004-01-01	14.2446382750084
2005-01-01	14.0204710659471
2006-01-01	13.8486498841446
2007-01-01	13.8128936166620
2008-01-01	13.8777834745507
2009-01-01	13.9717818007452
2010-01-01	14.0503371850136
2011-01-01	14.2458786151601
2012-01-01	14.3727158450585
2013-01-01	14.4642685150274
2014-01-01	14.5710084530711
2015-01-01	14.7095992458025
2016-01-01	14.8206666275239
2017-01-01	14.9623841813559