Year	Percent of Total
1960-01-01	3.44269776058788
1961-01-01	3.53624427644330
1962-01-01	3.64636919790077
1963-01-01	3.76594625310235
1964-01-01	3.88514499158521
1965-01-01	3.99981332941137
1966-01-01	4.11421962765088
1967-01-01	4.21505510135936
1968-01-01	4.30795994615084
1969-01-01	4.40060514339607
1970-01-01	4.49899708205791
1971-01-01	4.68845303308425
1972-01-01	4.86906382014104
1973-01-01	5.03295268079713
1974-01-01	5.17309649910723
1975-01-01	5.28618708224104
1976-01-01	5.43817612008154
1977-01-01	5.58061385743373
1978-01-01	5.70039142999988
1979-01-01	5.77459415354960
1980-01-01	5.79355025473372
1981-01-01	5.75179081830693
1982-01-01	5.66301159821912
1983-01-01	5.55924111430870
1984-01-01	5.48312864046763
1985-01-01	5.45862713535346
1986-01-01	5.57271507364214
1987-01-01	5.73830322032797
1988-01-01	5.95988603513355
1989-01-01	6.24092868920682
1990-01-01	6.58485798564420
1991-01-01	7.04473850896342
1992-01-01	7.55063392365552
1993-01-01	8.09276127513730
1994-01-01	8.64950405387336
1995-01-01	9.19819174797695
1996-01-01	9.57613233385656
1997-01-01	9.91197439739731
1998-01-01	10.22937033477000
1999-01-01	10.56976663142790
2000-01-01	10.95532807710500
2001-01-01	11.48370157219660
2002-01-01	12.07744463633870
2003-01-01	12.67128081334720
2004-01-01	13.15988445203970
2005-01-01	13.48665751693100
2006-01-01	13.72867821608760
2007-01-01	13.80331213566510
2008-01-01	13.79009825435710
2009-01-01	13.80853000925380
2010-01-01	13.92684850744900
2011-01-01	14.15947723757850
2012-01-01	14.47801655610990
2013-01-01	14.86449788196890
2014-01-01	15.28355845005130
2015-01-01	15.71705683405440
2016-01-01	16.13371299493630
2017-01-01	16.56903858749470