Year	Percent of Total
1960-01-01	41.8120813368614
1961-01-01	42.4820344352213
1962-01-01	43.3043113038345
1963-01-01	44.1932157394844
1964-01-01	44.8148664775809
1965-01-01	44.8888210952069
1966-01-01	44.5561830428338
1967-01-01	43.4661176259959
1968-01-01	41.8469210828999
1969-01-01	40.0478321887379
1970-01-01	38.2477304575641
1971-01-01	35.7020812980674
1972-01-01	33.4393227397525
1973-01-01	31.4124083305325
1974-01-01	29.4800314388171
1975-01-01	27.6097968778453
1976-01-01	26.3328941589811
1977-01-01	25.0710830393544
1978-01-01	24.0427214517130
1979-01-01	23.5536926859720
1980-01-01	23.6777564064875
1981-01-01	23.0208645713089
1982-01-01	23.0563771052349
1983-01-01	23.4140622306004
1984-01-01	23.6472997466847
1985-01-01	23.6249960328795
1986-01-01	24.4919286924583
1987-01-01	24.8275079069013
1988-01-01	24.9444491191329
1989-01-01	25.1642380167077
1990-01-01	25.5370927646212
1991-01-01	25.6184914236610
1992-01-01	25.7568442223810
1993-01-01	25.8599414059863
1994-01-01	25.7805058736374
1995-01-01	25.4751274352712
1996-01-01	25.1380324061723
1997-01-01	24.7198454044685
1998-01-01	24.2145047909291
1999-01-01	23.6044089401917
2000-01-01	22.8623367034364
2001-01-01	21.9050814803655
2002-01-01	20.7304141716567
2003-01-01	19.4318337400874
2004-01-01	18.1386055449854
2005-01-01	16.9384469049380
2006-01-01	15.7532636017190
2007-01-01	14.7526016081044
2008-01-01	13.9382285923149
2009-01-01	13.2709451317595
2010-01-01	12.7312749898039
2011-01-01	12.4980207083953
2012-01-01	12.3098993655461
2013-01-01	12.2139618401607
2014-01-01	12.2497159385238
2015-01-01	12.4166724908560
2016-01-01	12.8033690153177
2017-01-01	13.2636326692549