Do you actually read those? Those are graphs for what people want if a two state solution is available in the set of options in the study.
That twenty percent figure comes from if you remove all other possible options.
This its an example of ‘lies, damned lies, and statistics’ except as usual, it’s not the statistics doing the lying but the person misinterpreting them.
Edit: while I don’t think the author of this it’s biased, I think the methodology of the study is shitty. Not maliciously so, just it’s really hard to build studies that get to peoples underlying views.