Year % gross 1970 7.04989004135132 1971 5.47444009780884 1972 5.49455976486206 1973 5.36910009384155 1974 5.31124019622803 1975 6.46515989303589 1976 6.3092999458313 1977 6.29577016830444 1978 5.23266983032227 1979 5.13255977630615 1980 5.07340002059937 1981 5.16971015930176 1982 5.3111400604248 1983 5.37799978256226 1984 5.47508001327515 1985 5.45264005661011 1986 5.39600992202759 1987 5.32665014266968 1988 5.45611000061035 1989 5.56556987762451 1990 5.85130977630615 1991 5.91223001480103 1992 6.06070995330811 1993 6.39888000488281 1994 6.57141017913818 1995 6.6602201461792 1996 7.47419023513794 1997 7.64170980453491 1998 7.92791986465454 1999 7.89425992965698 2000 8.39624977111816 2001 8.93190956115723 2002 8.94344043731689 2003 9.81402969360352 2004 10.2872200012207 2005 10.4981603622437 2006 10.7773704528809 2007 11.3785800933838 2008 12.4409303665161 2009 14.0215396881104 2010 14.3778600692749 2011 15.25119972229 2012 15.4568796157837 2013 15.8645296096802 2014 16.0048408508301 2015 15.8183298110962 2016 15.580189704895 2017 15.7218999862671 2018 15.8872900009155 2019 16.5947093963623 2020 16.9075908660889 2021 17.5362300872803