Year	Percent of Total
1960-01-01	43.2230758208692
1961-01-01	43.9381940473950
1962-01-01	44.2950769402159
1963-01-01	44.3087890605352
1964-01-01	44.0592577894819
1965-01-01	43.6253866209964
1966-01-01	42.8116865388263
1967-01-01	41.9420582562339
1968-01-01	40.9969422084406
1969-01-01	39.9401237043678
1970-01-01	38.7753644518866
1971-01-01	37.5938132853302
1972-01-01	36.4490235868095
1973-01-01	35.2938275100645
1974-01-01	34.0768791288553
1975-01-01	32.7842750607590
1976-01-01	31.7198132892479
1977-01-01	30.4626967859819
1978-01-01	29.1447231583789
1979-01-01	27.9665263854439
1980-01-01	27.0413401335158
1981-01-01	26.1235325987334
1982-01-01	25.5263886455996
1983-01-01	25.1379608496970
1984-01-01	24.7567371709990
1985-01-01	24.2751988054119
1986-01-01	23.7636276595398
1987-01-01	23.0874155598611
1988-01-01	22.3704956598996
1989-01-01	21.7947436012549
1990-01-01	21.4601422591059
1991-01-01	21.3952211640622
1992-01-01	21.5715457888597
1993-01-01	21.8918854795674
1994-01-01	22.1610468636921
1995-01-01	22.2453625251848
1996-01-01	22.4958239078576
1997-01-01	22.4397836747613
1998-01-01	22.1504834594687
1999-01-01	21.7853942241667
2000-01-01	21.4562489141432
2001-01-01	20.8702693031889
2002-01-01	20.3544338605076
2003-01-01	19.9241050574272
2004-01-01	19.5334596479666
2005-01-01	19.1443990058432
2006-01-01	18.8475207945704
2007-01-01	18.5440001622811
2008-01-01	18.1853881246536
2009-01-01	17.7745403400008
2010-01-01	17.3405262489920
2011-01-01	16.9479543826846
2012-01-01	16.5682974518105
2013-01-01	16.1992241136972
2014-01-01	15.8429665391783
2015-01-01	15.5028976044856
2016-01-01	15.2371339566079
2017-01-01	14.9816845582048