Year	Percent of Total
1960-01-01	58.8552651605749
1961-01-01	57.9868714779807
1962-01-01	57.5743827619204
1963-01-01	57.5618394538800
1964-01-01	57.7448403636520
1965-01-01	57.9178318669065
1966-01-01	57.8073398990641
1967-01-01	57.6357247339308
1968-01-01	57.3572889003784
1969-01-01	57.0445481622220
1970-01-01	56.7443576243335
1971-01-01	55.6830380230946
1972-01-01	55.0039090570006
1973-01-01	54.6254958039117
1974-01-01	54.4137428982893
1975-01-01	54.2666052545723
1976-01-01	53.7343706015373
1977-01-01	53.1698008578931
1978-01-01	52.6193532934975
1979-01-01	52.1964190806912
1980-01-01	51.9457483755785
1981-01-01	51.2478993813668
1982-01-01	50.9112787522562
1983-01-01	50.8017966900264
1984-01-01	50.7606574773500
1985-01-01	50.7041426261037
1986-01-01	50.7203990665141
1987-01-01	50.7567853256645
1988-01-01	50.8045786133681
1989-01-01	50.9189252988749
1990-01-01	51.1441872234972
1991-01-01	50.7854191658074
1992-01-01	50.5677143831184
1993-01-01	50.4944672427848
1994-01-01	50.5345625942175
1995-01-01	50.6523494616042
1996-01-01	50.6338970810827
1997-01-01	50.7228083735681
1998-01-01	50.8843665155253
1999-01-01	51.0806243830620
2000-01-01	51.2768662265676
2001-01-01	51.1880015269639
2002-01-01	51.1543456394903
2003-01-01	51.1541182430287
2004-01-01	51.1737320826300
2005-01-01	51.2089012355595
2006-01-01	51.1024995623804
2007-01-01	51.0454052845920
2008-01-01	51.0442082574790
2009-01-01	51.1051135670546
2010-01-01	51.2239761392171
2011-01-01	51.2787433082355
2012-01-01	51.3958798640494
2013-01-01	51.5634714552171
2014-01-01	51.7686453386393
2015-01-01	52.0011731450907
2016-01-01	52.1388510479024
2017-01-01	52.3319883003073