While the Isle of Anglesey and Caerphilly were amongst the four local authorities with the highest proportions in 2011, Pembrokeshire previously had the eighth highest proportion.
Er bod Ynys Môn a Chaerffili ymhlith y pedwar awdurdod lleol â'r cyfrannau uchaf yn 2011, Sir Benfro oedd â'r wythfed gyfran uchaf cyn hynny.