 The electoral region was first used in the 1999 Welsh Assembly election, when the National Assembly for Wales was created.Each constituency elects one Member of the Senedd by the first past the post electoral system, and the region as a whole elects four additional or top-up Members of the Senedd, to create a degree of proportional representation.The additional member seats are allocated from closed lists by the D'Hondt method, with constituency results being taken into account in the allocation.