As the capital city of Wales, Cardiff is the main engine of growth in the Welsh economy; the city has been developing as a significant service centre and economic driver for the wider south east Wales economy. The city and the adjoining Vale of Glamorgan contribute a disproportionately high share of economic output in Wales. The Cardiff travel to work area has grown significantly since 1991; the 2001-based version includes much of the central South Wales Valleys in addition to the Vale of Glamorgan.