Year	Percent
1979-01-01	20.4388751175505
1980-01-01	21.2410290459219
1981-01-01	20.7481274398592
1982-01-01	19.4038233273325
1983-01-01	19.9824705172656
1984-01-01	19.9823401922432
1985-01-01	19.4675127308151
1986-01-01	20.6357504029400
1987-01-01	21.5080971542713
1988-01-01	22.0241345256629
1989-01-01	22.8732903067155
1990-01-01	24.1230411797030
1991-01-01	24.3933611164052
1992-01-01	24.2853866521862
1993-01-01	24.9576471651537
1994-01-01	26.1269890102702
1995-01-01	27.3363381650698
1996-01-01	29.3833287764150
1997-01-01	29.8101778368472
1998-01-01	30.8392598470536
1999-01-01	31.2502633848185
2000-01-01	34.2179549972608
2001-01-01	35.9976747148884
2002-01-01	37.9028159984212
2003-01-01	39.5848551764923
2004-01-01	41.1222540041045
2005-01-01	43.1107233931644
2006-01-01	45.9082954659888
2007-01-01	47.2780178760891
2008-01-01	49.0825201651472
2009-01-01	51.3535825630916
2010-01-01	52.7198943847221
2011-01-01	53.3857770177574
2012-01-01	53.9278387162180
2013-01-01	54.0139101437026
2014-01-01	54.0328264223594
2015-01-01	55.2333532073289
2016-01-01	56.7069886555592
2017-01-01	57.8563974853637