Year	Percent
1968-01-01	45.0511672244380
1969-01-01	44.8697940305445
1970-01-01	44.4091619746882
1971-01-01	44.9200710627656
1972-01-01	43.6143994562008
1973-01-01	44.5355354763634
1974-01-01	43.7206060016443
1975-01-01	43.6392309339342
1976-01-01	44.1490183612377
1977-01-01	44.5583704359279
1978-01-01	45.4479117379007
1979-01-01	45.5740602065942
1980-01-01	45.5219356809685
1981-01-01	44.8301633531910
1982-01-01	45.1287971940439
1983-01-01	46.2427663995204
1984-01-01	45.1546766847610
1985-01-01	45.4511435270366
1986-01-01	44.8204133212017
1987-01-01	45.1808117202464
1988-01-01	45.3476517353542
1989-01-01	46.1415735841350
1990-01-01	47.3176399958672
1991-01-01	48.6769923989948
1992-01-01	48.6226197220560
1993-01-01	48.7302161508761
1994-01-01	48.1607581513389
1995-01-01	48.6008557107548
1996-01-01	48.7440836842646
1997-01-01	49.5082246499644
1998-01-01	49.9182019611370
1999-01-01	50.0068473676502
2000-01-01	49.7031608485415
2001-01-01	49.1061989006602
2002-01-01	48.9378025421834
2003-01-01	49.4661970523460
2004-01-01	50.1641366488478
2005-01-01	50.8222491481198
2006-01-01	51.5030596872449
2007-01-01	52.5730276598239
2008-01-01	53.2397885205106
2009-01-01	53.6357493930500
2010-01-01	54.0484543331353
2011-01-01	54.4386503163317
2012-01-01	54.0994168268081
2013-01-01	55.8457477700305
2014-01-01	57.5175935274006
2015-01-01	59.3700889580600
2016-01-01	61.0821038486291
2017-01-01	63.3726179996000