Out of the 22 local authorities, Cardiff registered the highest volume of traffic in 2021 at 2.2bvk which was 11.1% higher than 2020.
O’r 22 awdurdod lleol, Caerdydd a gofrestrodd y lefel traffig uchaf yn 2021 ar 3bvk, a oedd 11.1% yn is na 2020.