Year	Percent of Total
1960-01-01	41.3125716169338
1961-01-01	41.8766965936777
1962-01-01	42.4471850627288
1963-01-01	42.9930329586968
1964-01-01	43.4526117406860
1965-01-01	43.7986925331688
1966-01-01	44.1601490462365
1967-01-01	44.3970967637346
1968-01-01	44.5313385469795
1969-01-01	44.5951403528237
1970-01-01	44.6056143340259
1971-01-01	44.7017609655478
1972-01-01	44.7158651535102
1973-01-01	44.6770785559851
1974-01-01	44.6310334900681
1975-01-01	44.6177465117183
1976-01-01	44.6842111200099
1977-01-01	44.7234505255527
1978-01-01	44.7567280922710
1979-01-01	44.7847851886218
1980-01-01	44.7904518417693
1981-01-01	44.9538106962715
1982-01-01	45.1144837373756
1983-01-01	45.2605803103875
1984-01-01	45.3795742562220
1985-01-01	45.4740148084776
1986-01-01	45.6810476815398
1987-01-01	45.8133990346578
1988-01-01	45.8940672177502
1989-01-01	45.9365115906634
1990-01-01	45.9455191280728
1991-01-01	45.9624603653933
1992-01-01	45.9246004105873
1993-01-01	45.8314970374426
1994-01-01	45.6799710995788
1995-01-01	45.4688111335019
1996-01-01	45.2457600582858
1997-01-01	44.9848890234743
1998-01-01	44.6838771015843
1999-01-01	44.3463906453272
2000-01-01	43.9765689389092
2001-01-01	43.6647310249547
2002-01-01	43.3201224276927
2003-01-01	42.9604379889954
2004-01-01	42.6058389760694
2005-01-01	42.2700436704070
2006-01-01	42.0063056231791
2007-01-01	41.7510364390138
2008-01-01	41.5063851412521
2009-01-01	41.2710248168591
2010-01-01	41.0441182440858
2011-01-01	40.8773948474954
2012-01-01	40.7063166212624
2013-01-01	40.5310856372219
2014-01-01	40.3446209761847
2015-01-01	40.1419302722839
2016-01-01	39.9770739353017
2017-01-01	39.7734644531596