Year	Percent of Total
1960-01-01	44.8746769244913
1961-01-01	45.1468395211097
1962-01-01	45.4143422988213
1963-01-01	45.6470020262696
1964-01-01	45.7935551831088
1965-01-01	45.8304186264390
1966-01-01	45.9737400586127
1967-01-01	45.9845004035522
1968-01-01	45.9009897801505
1969-01-01	45.7731070585973
1970-01-01	45.6228338096737
1971-01-01	45.4708238627460
1972-01-01	45.3160866934184
1973-01-01	45.1547536671464
1974-01-01	44.9710179285016
1975-01-01	44.7552697090433
1976-01-01	44.5751620112391
1977-01-01	44.3863736511435
1978-01-01	44.1947691870273
1979-01-01	43.9970444198985
1980-01-01	43.7795806059505
1981-01-01	43.5279174732631
1982-01-01	43.2512082814894
1983-01-01	42.9619168174278
1984-01-01	42.6722104536926
1985-01-01	42.3806931959885
1986-01-01	41.8434926997562
1987-01-01	41.3377171719650
1988-01-01	40.8546337346785
1989-01-01	40.3857697626063
1990-01-01	39.9358780159940
1991-01-01	39.4038887805241
1992-01-01	38.9217809056519
1993-01-01	38.4959810010961
1994-01-01	38.1250309967006
1995-01-01	37.7988510304993
1996-01-01	37.5548160456988
1997-01-01	37.3153181307511
1998-01-01	37.0853440199242
1999-01-01	36.8602759018723
2000-01-01	36.6233123924395
2001-01-01	36.3164713894197
2002-01-01	35.9797639952036
2003-01-01	35.6074778093070
2004-01-01	35.2012031779228
2005-01-01	34.7621422663043
2006-01-01	34.0984314646235
2007-01-01	33.4846613161063
2008-01-01	32.8860885903984
2009-01-01	32.2623098586409
2010-01-01	31.6014953705221
2011-01-01	30.9368823233041
2012-01-01	30.2122918785079
2013-01-01	29.4848304458790
2014-01-01	28.8375337854027
2015-01-01	28.3077739043209
2016-01-01	27.7852047733534
2017-01-01	27.3772537560837