Year % 1976 3.771558342609701 1977 3.4779154446870204 1978 3.5353262792694498 1979 4.7280563579459995 1980 9.293216528685221 1981 3.47687688377699 1982 3.3319160415168 1983 4.1271731312811 1984 3.4321539122587397 1985 4.38252984066758 1986 5.05073314328639 1987 7.1325912588810505 1988 3.4911944517592994 1989 5.0875049307922 1990 6.0246124899831 1991 4.37385188357416 1992 4.41501092987446 1993 3.645623990027709 1994 5.160642661588236 1995 5.6005288827404005 1996 10.623609515022148 1997 17.560429836765483 1998 29.959997570492686 1999 26.54084949947525 2000 34.04043357042635 2001 23.560383366331962 2002 25.638852631883765 2003 18.394224580444615 2004 18.561438348529897 2005 19.48858453646499 2006 23.37359149767284 2007 29.592768693879922 2008 39.98610046239405 2009 25.592258508709378 2010 28.322315659719607 2011 27.019091340665504 2012 24.809438577969487 2013 24.452064443526 2014 24.605005488557023 2015 29.743607052680154 2016 36.176644298272414 2017 24.989020584624967 2018 40.3699780089678 2019 31.344802571491034 2020 32.39056154280106 2021 25.794156280314905 2022 23.210121648548352