Year	Percent of Total
1960-01-01	25.0743031127938
1961-01-01	25.0181388196651
1962-01-01	24.8965719094034
1963-01-01	24.7458198487103
1964-01-01	24.6336485580585
1965-01-01	24.5839830698121
1966-01-01	24.6071675890643
1967-01-01	24.6197289820857
1968-01-01	24.6305708500145
1969-01-01	24.6446044393062
1970-01-01	24.6587789401244
1971-01-01	24.5943692605347
1972-01-01	24.5565436404945
1973-01-01	24.5054247302347
1974-01-01	24.3803403199776
1975-01-01	24.1483452204666
1976-01-01	23.8941162935872
1977-01-01	23.5102140085137
1978-01-01	23.0254994802168
1979-01-01	22.4990026099263
1980-01-01	21.9663534155825
1981-01-01	21.3923628084196
1982-01-01	20.8369468835100
1983-01-01	20.2869120365666
1984-01-01	19.7174876854428
1985-01-01	19.1242224141183
1986-01-01	18.5740592288909
1987-01-01	18.0111803842710
1988-01-01	17.4549527304354
1989-01-01	16.9347960598712
1990-01-01	16.4678229884510
1991-01-01	16.0946475217294
1992-01-01	15.7629750689151
1993-01-01	15.4746826246871
1994-01-01	15.2218147035686
1995-01-01	14.9967235286413
1996-01-01	14.8193253604293
1997-01-01	14.6601355487177
1998-01-01	14.5212107019626
1999-01-01	14.4080073187842
2000-01-01	14.3254249449080
2001-01-01	14.2336325993259
2002-01-01	14.1793339417692
2003-01-01	14.1488946375720
2004-01-01	14.1232324211778
2005-01-01	14.0911371578825
2006-01-01	14.1003528630031
2007-01-01	14.0959991392180
2008-01-01	14.0790591839302
2009-01-01	14.0516375304436
2010-01-01	14.0107467616629
2011-01-01	13.9928395831929
2012-01-01	13.9443016498824
2013-01-01	13.8748441375612
2014-01-01	13.7996606835053
2015-01-01	13.7267106402485
2016-01-01	13.6081817887813
2017-01-01	13.5175261413850