Year	Percent of Total
1960-01-01	27.1379193072878
1961-01-01	27.1398864161447
1962-01-01	27.1376916990937
1963-01-01	27.1777585195253
1964-01-01	27.2497250100773
1965-01-01	27.3147589376440
1966-01-01	27.3100016984205
1967-01-01	27.3061196270544
1968-01-01	27.2711019347443
1969-01-01	27.1816339623091
1970-01-01	27.0300773453889
1971-01-01	26.6754277743306
1972-01-01	26.3130738025763
1973-01-01	25.9310396817035
1974-01-01	25.5153669322000
1975-01-01	25.0662877897997
1976-01-01	24.7570295892382
1977-01-01	24.3645168157297
1978-01-01	23.9464607056398
1979-01-01	23.5852419963021
1980-01-01	23.3203206637365
1981-01-01	23.0592377280795
1982-01-01	22.9271110661704
1983-01-01	22.8789983513658
1984-01-01	22.8397063742862
1985-01-01	22.7756543629625
1986-01-01	22.7795560224994
1987-01-01	22.7433526827461
1988-01-01	22.6863815399249
1989-01-01	22.6302267690629
1990-01-01	22.5650251052885
1991-01-01	22.4832878200210
1992-01-01	22.3718988096852
1993-01-01	22.2196522847335
1994-01-01	22.0158536244490
1995-01-01	21.7593218114367
1996-01-01	21.4923641933600
1997-01-01	21.2001774349256
1998-01-01	20.8674612173440
1999-01-01	20.4821065981937
2000-01-01	20.0395506927083
2001-01-01	19.3564805791773
2002-01-01	18.6879527536654
2003-01-01	18.0291604380568
2004-01-01	17.3866159063363
2005-01-01	16.7731080074109
2006-01-01	16.2975974302526
2007-01-01	15.8428399698045
2008-01-01	15.4202960405671
2009-01-01	15.0549487309279
2010-01-01	14.7654637632399
2011-01-01	14.6393643131017
2012-01-01	14.5580239466938
2013-01-01	14.5225723926663
2014-01-01	14.5337738694044
2015-01-01	14.5962074076904
2016-01-01	14.6914517979719
2017-01-01	14.8232171295891