Year	Percent
1960-01-01	16.748400000000000
1961-01-01	15.330900000000000
1962-01-01	16.427900000000000
1963-01-01	19.353900000000000
1964-01-01	19.942300000000000
1965-01-01	20.236500000000000
1966-01-01	19.889900000000000
1967-01-01	21.061800000000000
1968-01-01	23.550600000000000
1969-01-01	26.342700000000000
1970-01-01	27.356700000000000
1971-01-01	29.276000000000000
1972-01-01	30.181700000000000
1973-01-01	30.075000000000000
1974-01-01	29.421500000000000
1975-01-01	29.843000000000004
1976-01-01	30.678100000000000
1977-01-01	30.474300000000000
1978-01-01	28.808000000000003
1979-01-01	30.146600000000000
1980-01-01	32.630100000000000
1981-01-01	36.294700000000000
1982-01-01	41.311800000000000
1983-01-01	43.090900000000000
1984-01-01	42.496600000000000
1985-01-01	42.883400000000000
1986-01-01	47.079200000000000
1987-01-01	49.877200000000000
1988-01-01	52.572600000000000
1989-01-01	53.355600000000000
1990-01-01	37.944100000000000
1991-01-01	31.741900000000000
1992-01-01	29.763500000000000
1993-01-01	30.066500000000000
1994-01-01	31.627200000000000
1995-01-01	31.191400000000000
1996-01-01	34.352900000000000
1997-01-01	34.049100000000000
1998-01-01	34.323800000000000
1999-01-01	33.842400000000000
2000-01-01	33.964800000000000
2001-01-01	38.256300000000000
2002-01-01	42.199900000000000
2003-01-01	41.344400000000000
2004-01-01	40.818300000000000
2005-01-01	41.201900000000000
2006-01-01	40.466800000000000
2007-01-01	38.846800000000000
2008-01-01	39.665600000000000
2009-01-01	38.596900000000000
2010-01-01	39.011900000000000
2011-01-01	37.529300000000000
2012-01-01	37.785600000000000
2013-01-01	38.833600000000000
2014-01-01	39.774200000000000
2015-01-01	39.907300000000000
2016-01-01	42.794100000000000