Year	Percent of Total
1960-01-01	45.2771984706291
1961-01-01	45.9056207300719
1962-01-01	46.3248582929434
1963-01-01	46.6365161135737
1964-01-01	46.8928581823827
1965-01-01	47.0990114871041
1966-01-01	47.1809926198250
1967-01-01	47.2642246122174
1968-01-01	47.3035731210312
1969-01-01	47.2610492952432
1970-01-01	47.1165965526837
1971-01-01	47.3480083017477
1972-01-01	47.5304758159654
1973-01-01	47.6410351601776
1974-01-01	47.6798647444538
1975-01-01	47.6422032117665
1976-01-01	47.5711632518665
1977-01-01	47.3870164757754
1978-01-01	47.0902745295578
1979-01-01	46.7803687059906
1980-01-01	46.5526690021158
1981-01-01	45.9902687610967
1982-01-01	45.6237623762376
1983-01-01	45.3819101282232
1984-01-01	45.1215177084698
1985-01-01	44.7771963546183
1986-01-01	44.6605491602189
1987-01-01	44.3999541073887
1988-01-01	44.0629398753268
1989-01-01	43.7447198164268
1990-01-01	43.4599471080020
1991-01-01	43.2745937235122
1992-01-01	43.1588589778558
1993-01-01	43.0385191482471
1994-01-01	42.8676973729881
1995-01-01	42.6554504911506
1996-01-01	42.2082966734682
1997-01-01	41.7258557981282
1998-01-01	41.3020444320925
1999-01-01	40.9846627563529
2000-01-01	40.7415644016740
2001-01-01	40.4292034009977
2002-01-01	40.1188378603083
2003-01-01	39.7822613606807
2004-01-01	39.3963540742297
2005-01-01	38.9657473074058
2006-01-01	38.3247290599731
2007-01-01	37.6690225095256
2008-01-01	37.0052096091977
2009-01-01	36.3442052183774
2010-01-01	35.6906544613318
2011-01-01	34.9862694111643
2012-01-01	34.3438243426660
2013-01-01	33.7235350004794
2014-01-01	33.0943945589063
2015-01-01	32.4541871701810
2016-01-01	31.9544139047401
2017-01-01	31.4208620132860