Year	Percent of Total
1960-01-01	30.2638998185348
1961-01-01	29.4090392276000
1962-01-01	28.4783769883077
1963-01-01	27.5208381935823
1964-01-01	26.6305426970886
1965-01-01	25.8656469802910
1966-01-01	25.3361831112863
1967-01-01	24.8587807772823
1968-01-01	24.4763484371333
1969-01-01	24.2259952056165
1970-01-01	24.1134748325826
1971-01-01	24.0342817456257
1972-01-01	24.1109454761026
1973-01-01	24.2717131928187
1974-01-01	24.3945335528305
1975-01-01	24.4062456762094
1976-01-01	24.4871902135936
1977-01-01	24.3582395964023
1978-01-01	24.0942847288216
1979-01-01	23.8178175596498
1980-01-01	23.5840768894456
1981-01-01	23.1353615424482
1982-01-01	22.8224316248185
1983-01-01	22.5481927490263
1984-01-01	22.1729781911602
1985-01-01	21.6429166125418
1986-01-01	21.1616786178923
1987-01-01	20.5210645920376
1988-01-01	19.7882724481146
1989-01-01	19.0848515844458
1990-01-01	18.4747414823116
1991-01-01	17.9202643764690
1992-01-01	17.4375152563227
1993-01-01	17.0181883314851
1994-01-01	16.6267279610142
1995-01-01	16.2457086409478
1996-01-01	15.8962856773414
1997-01-01	15.5872264520795
1998-01-01	15.3048222975614
1999-01-01	15.0381261812364
2000-01-01	14.7831070591769
2001-01-01	14.5784621505047
2002-01-01	14.3657951893197
2003-01-01	14.1586916067282
2004-01-01	13.9773351089532
2005-01-01	13.8294315099235
2006-01-01	13.6868957520370
2007-01-01	13.5878307416403
2008-01-01	13.5150519980831
2009-01-01	13.4417648668929
2010-01-01	13.3546642295908
2011-01-01	13.3036480436126
2012-01-01	13.2322591906037
2013-01-01	13.1475941783571
2014-01-01	13.0649248164092
2015-01-01	12.9912205167514
2016-01-01	12.9357482227601
2017-01-01	12.8868101168417