Year	Percent of Total
1960-01-01	40.2772397563995
1961-01-01	40.6158434047831
1962-01-01	40.9540777547459
1963-01-01	41.2594416854017
1964-01-01	41.4790589709792
1965-01-01	41.5913567871818
1966-01-01	41.7646416425601
1967-01-01	41.8171041228157
1968-01-01	41.7783000435543
1969-01-01	41.6915080634910
1970-01-01	41.5798208050009
1971-01-01	41.5379489433759
1972-01-01	41.4587121651380
1973-01-01	41.3472805254713
1974-01-01	41.2027325690642
1975-01-01	41.0279283129603
1976-01-01	40.9537759244084
1977-01-01	40.8258661182455
1978-01-01	40.6638745468546
1979-01-01	40.4913971409588
1980-01-01	40.3218785406416
1981-01-01	40.2456353849462
1982-01-01	40.1606971500300
1983-01-01	40.0614253966818
1984-01-01	39.9345479725039
1985-01-01	39.7730702226605
1986-01-01	39.7039305520370
1987-01-01	39.5715875613407
1988-01-01	39.3910509827602
1989-01-01	39.1797613829166
1990-01-01	38.9551008535636
1991-01-01	38.7567101333566
1992-01-01	38.5257869240955
1993-01-01	38.2605172262857
1994-01-01	37.9555194968532
1995-01-01	37.6077845586778
1996-01-01	37.2780183470950
1997-01-01	36.9094519091442
1998-01-01	36.5070836781533
1999-01-01	36.0838365850652
2000-01-01	35.6522079727685
2001-01-01	35.3046393735305
2002-01-01	34.9478743223241
2003-01-01	34.5876482749426
2004-01-01	34.2305838323999
2005-01-01	33.8800566934150
2006-01-01	33.5608414919092
2007-01-01	33.2464630240268
2008-01-01	32.9375237767481
2009-01-01	32.6331110800803
2010-01-01	32.3321387067053
2011-01-01	32.0563019115635
2012-01-01	31.7753956282669
2013-01-01	31.4910261419706
2014-01-01	31.2063383592992
2015-01-01	30.9209337585908
2016-01-01	30.6515718031049
2017-01-01	30.3850621343661