Year % gross 1979 4.49816989898682 2005 11.5016603469849 2007 11.5655498504639 2008 11.6187200546265 2013 11.2012500762939 2014 15.5887002944946 2015 21.4308109283447 2016 22.2944602966309 2017 20.5279006958008 2018 20.7348003387451 2019 20.9363899230957 2020 21.2619400024414 2021 17.6948509216309