Most of the analysis is presented at the Great Britain level, but where sample sizes allow, conclusions are drawn regarding the position in Wales.
Cyflwynir y rhan fwyaf o’r dadansoddiad ar lefel Prydain Fawr, ond deuir i gasgliadau ynglŷn â’r sefyllfa yng Nghymru pan fo maint samplau’n caniatáu hynny.