Year	Percent
1979-01-01	20.9630157212321
1980-01-01	21.8249587070970
1981-01-01	21.2061585481202
1982-01-01	19.9717440828230
1983-01-01	20.6540780196924
1984-01-01	20.6643589212937
1985-01-01	20.1735945236378
1986-01-01	21.3959100314075
1987-01-01	22.2245859292578
1988-01-01	22.7771223958836
1989-01-01	23.6166352746713
1990-01-01	24.8443151460173
1991-01-01	25.3711293477534
1992-01-01	25.2619544304627
1993-01-01	26.2093058117726
1994-01-01	27.6722264765488
1995-01-01	28.5062346802376
1996-01-01	30.8393468730599
1997-01-01	31.1908421568977
1998-01-01	32.2811656622280
1999-01-01	32.3844561464875
2000-01-01	35.3333463137414
2001-01-01	37.0978355966582
2002-01-01	39.0552726847815
2003-01-01	40.8168849821540
2004-01-01	42.4108315857458
2005-01-01	44.3929130939879
2006-01-01	47.2169612228304
2007-01-01	48.5530494131540
2008-01-01	50.0878894290730
2009-01-01	52.8725236846290
2010-01-01	54.1432547603038
2011-01-01	54.9732430744690
2012-01-01	55.6601365360808
2013-01-01	55.7883919585112
2014-01-01	56.1693447779870
2015-01-01	57.2649825999790
2016-01-01	58.8242590980393
2017-01-01	60.0929370260695