Year	Percent of Total
1960-01-01	40.7377198732705
1961-01-01	41.1958237757443
1962-01-01	41.6844673628027
1963-01-01	42.1269993047529
1964-01-01	42.4170712795811
1965-01-01	42.5224673695965
1966-01-01	42.6536337977441
1967-01-01	42.6190892488620
1968-01-01	42.4713496228687
1969-01-01	42.2859527004977
1970-01-01	42.1012984473814
1971-01-01	42.0645672883815
1972-01-01	41.9715049170264
1973-01-01	41.8470183852517
1974-01-01	41.7076923744719
1975-01-01	41.5582084456254
1976-01-01	41.4739085673429
1977-01-01	41.3707422257744
1978-01-01	41.2431919573874
1979-01-01	41.0807843578785
1980-01-01	40.8803947723612
1981-01-01	40.7411641714361
1982-01-01	40.5658531248805
1983-01-01	40.3472351334081
1984-01-01	40.0688992765559
1985-01-01	39.7195621677932
1986-01-01	39.4535211273543
1987-01-01	39.0709172784355
1988-01-01	38.6065677015240
1989-01-01	38.1046197285399
1990-01-01	37.5833925109997
1991-01-01	37.0642029129484
1992-01-01	36.5633117896962
1993-01-01	36.0565885942352
1994-01-01	35.5146417923506
1995-01-01	34.9339554619255
1996-01-01	34.3556926845676
1997-01-01	33.7665856650183
1998-01-01	33.1830595395656
1999-01-01	32.6353478035026
2000-01-01	32.1419058561556
2001-01-01	31.8257161138006
2002-01-01	31.5573049934854
2003-01-01	31.3308980803191
2004-01-01	31.1242172358375
2005-01-01	30.9142902237078
2006-01-01	30.8060721025636
2007-01-01	30.6383629765369
2008-01-01	30.4264297848542
2009-01-01	30.2016839525717
2010-01-01	29.9781943881533
2011-01-01	29.5543505591188
2012-01-01	29.1693878110592
2013-01-01	28.7879073544192
2014-01-01	28.3619740027874
2015-01-01	27.8772866075465
2016-01-01	27.3726481213854
2017-01-01	26.8311084851964