Category 2018 2015 2013 2010 2007
Don't know 0 1 0 1 1
I have never heard of it (%) 29 38 26 33 35
I've heard of it but I do not know what it is (%) 30 30 30 28 30
I've heard of it and I know what it is (%) 41 31 44 38 35