Year	Percent of Total
1960-01-01	41.2223001236795
1961-01-01	41.3684587701943
1962-01-01	41.3280177665366
1963-01-01	41.2114640050707
1964-01-01	41.1299708287359
1965-01-01	41.1053347077190
1966-01-01	40.7777368227055
1967-01-01	40.6310633752153
1968-01-01	40.5312142038946
1969-01-01	40.2908613645505
1970-01-01	39.8074272108275
1971-01-01	39.4205449407688
1972-01-01	38.7504077416549
1973-01-01	37.9146536758670
1974-01-01	37.1017416807520
1975-01-01	36.3907412583689
1976-01-01	35.1590788072417
1977-01-01	34.0206392145076
1978-01-01	32.9532864653627
1979-01-01	31.9375223399448
1980-01-01	31.0096218816725
1981-01-01	30.1248228864449
1982-01-01	29.4259948660744
1983-01-01	28.8233721085707
1984-01-01	28.2594365690772
1985-01-01	27.7376194497829
1986-01-01	27.4422386159926
1987-01-01	27.2796067611369
1988-01-01	27.2065465036332
1989-01-01	27.2016823824707
1990-01-01	27.2412405997096
1991-01-01	27.1637524873666
1992-01-01	27.0974722813842
1993-01-01	27.0087264345106
1994-01-01	26.8954349698536
1995-01-01	26.7583609018376
1996-01-01	26.4172471352204
1997-01-01	26.0824395102064
1998-01-01	25.6992789883922
1999-01-01	25.2883233688976
2000-01-01	24.8979931717878
2001-01-01	23.9336183670180
2002-01-01	23.1671440436548
2003-01-01	22.4791245186337
2004-01-01	21.7873389670482
2005-01-01	21.1099432740313
2006-01-01	20.8919013176849
2007-01-01	20.5840676615153
2008-01-01	20.2497674085737
2009-01-01	19.9954145331508
2010-01-01	19.8573248062436
2011-01-01	19.4690324251459
2012-01-01	19.2698630584698
2013-01-01	19.1542657929565
2014-01-01	19.0266561030464
2015-01-01	18.8658945636352
2016-01-01	18.8014130550728
2017-01-01	18.6907854166277