Year	Percent of Total
1960-01-01	4.96614937185630
1961-01-01	4.92769776787024
1962-01-01	4.86866301904783
1963-01-01	4.79674355495251
1964-01-01	4.72146019642184
1965-01-01	4.65923013713459
1966-01-01	4.62907371620481
1967-01-01	4.62044579715334
1968-01-01	4.62824672537811
1969-01-01	4.64246269338404
1970-01-01	4.65850240662889
1971-01-01	4.85971238929159
1972-01-01	5.07181418757311
1973-01-01	5.29830287470591
1974-01-01	5.54313831442092
1975-01-01	5.80561855414108
1976-01-01	6.14634962461049
1977-01-01	6.49950358055726
1978-01-01	6.85762634036004
1979-01-01	7.21465608398201
1980-01-01	7.57817552641967
1981-01-01	7.60227912269387
1982-01-01	7.57267563361052
1983-01-01	7.50774913121607
1984-01-01	7.42629405903828
1985-01-01	7.33899661825017
1986-01-01	7.12432823655543
1987-01-01	6.94152947855000
1988-01-01	6.78453114433257
1989-01-01	6.64491845924164
1990-01-01	6.52361638100222
1991-01-01	6.64652140975340
1992-01-01	6.77814594202379
1993-01-01	6.91193346744252
1994-01-01	7.04386707588104
1995-01-01	7.16852569188407
1996-01-01	7.22723195796395
1997-01-01	7.27679772091124
1998-01-01	7.32071530876910
1999-01-01	7.35802811248818
2000-01-01	7.38424081555403
2001-01-01	7.30367215195363
2002-01-01	7.23218741089250
2003-01-01	7.17640232360528
2004-01-01	7.13199406939822
2005-01-01	7.10151504790088
2006-01-01	7.03701451390578
2007-01-01	6.94569322956673
2008-01-01	6.85022591708338
2009-01-01	6.79423505605230
2010-01-01	6.81584970454533
2011-01-01	7.02935175697393
2012-01-01	7.32332973649452
2013-01-01	7.68944899720582
2014-01-01	8.11846849677554
2015-01-01	8.60765265200302
2016-01-01	9.17543742148793
2017-01-01	9.79846345855145