Year	Percent of Total
1960-01-01	31.8741593524298
1961-01-01	32.0993655484891
1962-01-01	32.0915251864652
1963-01-01	31.8947060872400
1964-01-01	31.6129460221129
1965-01-01	31.2980574017956
1966-01-01	30.9212652761109
1967-01-01	30.4939342723486
1968-01-01	30.0276701010717
1969-01-01	29.5440360706027
1970-01-01	29.0675190548556
1971-01-01	28.4976459956545
1972-01-01	28.0199944587354
1973-01-01	27.6060489415361
1974-01-01	27.2069912095726
1975-01-01	26.8101051252204
1976-01-01	26.6106780403396
1977-01-01	26.3391367290547
1978-01-01	26.0677163185380
1979-01-01	25.8915102289939
1980-01-01	25.8454809221790
1981-01-01	25.8583915526218
1982-01-01	25.9873965296331
1983-01-01	26.1878526116817
1984-01-01	26.3765566614733
1985-01-01	26.5135337986463
1986-01-01	26.6687842656896
1987-01-01	26.7758357495368
1988-01-01	26.8293071317019
1989-01-01	26.8175819955847
1990-01-01	26.7294947524133
1991-01-01	26.6740831703338
1992-01-01	26.4441929667683
1993-01-01	26.1649106994882
1994-01-01	25.8460688512650
1995-01-01	25.5347661319884
1996-01-01	25.0178004845979
1997-01-01	24.5702629556377
1998-01-01	24.1546792079398
1999-01-01	23.7045357461185
2000-01-01	23.2045777327926
2001-01-01	22.7399194253635
2002-01-01	22.2157599797362
2003-01-01	21.6819102521485
2004-01-01	21.2086779158048
2005-01-01	20.8375611572074
2006-01-01	20.5187091603519
2007-01-01	20.2459147966134
2008-01-01	20.0402636235991
2009-01-01	19.9076012792112
2010-01-01	19.8450025285139
2011-01-01	19.8428026129946
2012-01-01	19.9261674700588
2013-01-01	20.0711702047577
2014-01-01	20.2252624575833