Year	Percent of Total
1960-01-01	47.5897174151452
1961-01-01	47.9439145773807
1962-01-01	48.1529602256405
1963-01-01	48.2491224946586
1964-01-01	48.2701077718988
1965-01-01	48.2324823007116
1966-01-01	48.5259414949595
1967-01-01	48.6738455485515
1968-01-01	48.6774913616488
1969-01-01	48.5339977320307
1970-01-01	48.2440145122322
1971-01-01	47.9677851340363
1972-01-01	47.7617929355496
1973-01-01	47.6207023868992
1974-01-01	47.5306697635436
1975-01-01	47.4532198734882
1976-01-01	45.8900167144486
1977-01-01	44.2936159958786
1978-01-01	42.6562495677218
1979-01-01	41.0460476354850
1980-01-01	39.5692119401175
1981-01-01	38.2324365237735
1982-01-01	37.2360122187060
1983-01-01	36.4902819600329
1984-01-01	35.8578578034053
1985-01-01	35.2717581500525
1986-01-01	35.1015079590413
1987-01-01	34.7216502369322
1988-01-01	34.2815752022913
1989-01-01	33.9683898551160
1990-01-01	33.8526328189422
1991-01-01	33.7590555277253
1992-01-01	33.8359790237083
1993-01-01	34.0013347626611
1994-01-01	34.1133588231660
1995-01-01	34.0970963932535
1996-01-01	33.8555137811197
1997-01-01	33.5424187527689
1998-01-01	33.1694687581246
1999-01-01	32.7687402436387
2000-01-01	32.3616079933953
2001-01-01	32.0938167203918
2002-01-01	31.7962752875514
2003-01-01	31.4853419395002
2004-01-01	31.1692968417641
2005-01-01	30.8432175024953
2006-01-01	30.4352309208478
2007-01-01	30.0114772270235
2008-01-01	29.5759665183598
2009-01-01	29.1362781611889
2010-01-01	28.7046452880900
2011-01-01	28.3198109817923
2012-01-01	27.9507407690145
2013-01-01	27.5994396726509
2014-01-01	27.2639835890847
2015-01-01	26.9415843588668
2016-01-01	26.6908203908533
2017-01-01	26.4347659397730