Year	Percent of Total
1960-01-01	53.7012474414279
1961-01-01	53.5854205977299
1962-01-01	53.5785305683224
1963-01-01	53.6367120987637
1964-01-01	53.7078286501897
1965-01-01	53.7662688919666
1966-01-01	53.5790323538713
1967-01-01	53.4345230717196
1968-01-01	53.3272814763316
1969-01-01	53.2663915706660
1970-01-01	53.2579890939176
1971-01-01	53.0396469558109
1972-01-01	52.9029826506832
1973-01-01	52.8314340581520
1974-01-01	52.8051463577160
1975-01-01	52.8106913540066
1976-01-01	52.6345966697923
1977-01-01	52.5261644990937
1978-01-01	52.4718213896365
1979-01-01	52.4650996006373
1980-01-01	52.5051311844820
1981-01-01	52.3450276462540
1982-01-01	52.2496190741556
1983-01-01	52.2064415982664
1984-01-01	52.2006715731491
1985-01-01	52.2186899061106
1986-01-01	52.0692942773836
1987-01-01	51.9948209033714
1988-01-01	51.9682558547678
1989-01-01	51.9561448480538
1990-01-01	51.9325136421556
1991-01-01	51.7850831794391
1992-01-01	51.6704092660482
1993-01-01	51.5847142145866
1994-01-01	51.5512343899062
1995-01-01	51.5987164456056
1996-01-01	51.4621698522236
1997-01-01	51.4044831153426
1998-01-01	51.4149487397885
1999-01-01	51.4597907603722
2000-01-01	51.5061850434699
2001-01-01	51.4057718900918
2002-01-01	51.3383101883716
2003-01-01	51.2920803144843
2004-01-01	51.2651445386664
2005-01-01	51.2551369391393
2006-01-01	51.1059342064398
2007-01-01	51.0088627115250
2008-01-01	50.9462777179061
2009-01-01	50.9016144754395
2010-01-01	50.8683744031978
2011-01-01	50.7345541569285
2012-01-01	50.6440265124231
2013-01-01	50.5948697398802
2014-01-01	50.5919968378872
2015-01-01	50.6382153255383
2016-01-01	50.6338111286692
2017-01-01	50.6980564098436