Year	Percent of Total
1960-01-01	10.1752377985545
1961-01-01	10.3139619967410
1962-01-01	10.4522428264071
1963-01-01	10.5929133493845
1964-01-01	10.7381441165876
1965-01-01	10.8928826379528
1966-01-01	11.0921387927293
1967-01-01	11.2922674604479
1968-01-01	11.4927056131938
1969-01-01	11.6925644210536
1970-01-01	11.8848859027278
1971-01-01	12.0954058860156
1972-01-01	12.2840793216256
1973-01-01	12.4556624057965
1974-01-01	12.6176106879089
1975-01-01	12.7713978251971
1976-01-01	12.9896275655785
1977-01-01	13.2073826121576
1978-01-01	13.3942451726764
1979-01-01	13.5033946436648
1980-01-01	13.5120644540116
1981-01-01	13.4768576466633
1982-01-01	13.3390960553775
1983-01-01	13.1614286031931
1984-01-01	13.0339757475835
1985-01-01	13.0090693903434
1986-01-01	13.1233120771504
1987-01-01	13.3246762415751
1988-01-01	13.5806502572734
1989-01-01	13.8398285376271
1990-01-01	14.0717108884350
1991-01-01	14.3232768807530
1992-01-01	14.5508852020216
1993-01-01	14.7596734638486
1994-01-01	14.9587504926704
1995-01-01	15.1553976621950
1996-01-01	15.3938041843617
1997-01-01	15.6145864062086
1998-01-01	15.8280060388968
1999-01-01	16.0466031910609
2000-01-01	16.2774747799543
2001-01-01	16.5152569719470
2002-01-01	16.7612378837916
2003-01-01	17.0051697579334
2004-01-01	17.2280155810445
2005-01-01	17.4204065279607
2006-01-01	17.6259223531766
2007-01-01	17.7963846151388
2008-01-01	17.9546876617632
2009-01-01	18.1345355639178
2010-01-01	18.3596646463157
2011-01-01	18.6097205291705
2012-01-01	18.9081224881343
2013-01-01	19.2396798250691
2014-01-01	19.5772211316339
2015-01-01	19.9025895261675
2016-01-01	20.2026220906777
2017-01-01	20.4884451701441