Year % gross 1979 4.08945989608765 2005 11.1586303710938 2007 11.2565603256226 2008 11.3071002960205 2009 11.3458700180054 2010 11.509349822998 2011 12.4907703399658 2012 14.301609992981 2013 14.397310256958 2014 17.6277294158936 2015 21.4036903381348 2016 22.2092895507813 2017 20.9970397949219 2018 21.2317504882813 2019 21.464469909668 2020 21.794620513916 2021 18.319730758667