Previously accounting for over half responses in the 2011 Census, this marked a 14.0 percentage point decrease over the decade from 57.6% (1.8 million) in 2011.
Dyma oedd dros hanner yr ymatebion yng Nghyfrifiad 2011, ac felly roedd hyn yn ostyngiad o 14.0 pwynt canran dros y degawd o 57.6% (1.8 miliwn) yn 2011.