Annual % of total
1960 22.840103159252095
1961 25.11756569847856
1962 27.577830100534445
1963 30.276978541962773
1964 34.341504828610844
1965 38.42248035055992
1966 41.70791216451725
1967 43.4761839770711
1968 46.209520274659
1969 48.21571593841773
1970 52.04775666287183
1971 54.97118373012281
1972 54.668011995851906
1973 53.06435003036625
1974 47.20271186440678
1975 50.35889119139863
1976 50.02538500592316
1977 50.68374087379765
1978 50.696393867415246
1979 48.431044401443444
1980 47.277556440903055
1981 44.841962094556635
1982 45.24752784103316
1983 45.07306512718744
1984 41.45883335072524
1985 42.29203229203229
1986 49.01261852142297
1987 47.21194879089616
1988 48.901962217268974
1989 44.1426377751237
1990 41.74898453938341
1991 44.917210424710426
1992 47.70397133446097
1993 47.110509490509486
1994 46.35611401218451
1995 45.86230514096186
1996 47.534389284219344
1997 48.29914351851852
1998 47.498106523741725
1999 46.968457276426285
2000 44.20848652796726
2001 45.73369359472706
2002 45.03281100586378
2003 47.407483982683985
2004 46.79750657779337
2005 47.31527348341018
2006 46.623044638748276
2007 46.39934793001243
2008 47.5375984288787
2009 50.661773853717264
2010 51.63833098525406
2011 52.94646123260437
2012 49.83042122999158
2013 50.59632543214988
2014 55.08227706299911
2015 55.34011449579832
2016 53.48485899067006