Change is assessed since 2015, as this was the year of the Well-being of Future Generations Act, although the milestones themselves were not set until later.
Asesir newid ers 2015, gan mai hon oedd blwyddyn Deddf Llesiant Cenedlaethau'r Dyfodol, er na chafodd y cerrig milltir eu hunain eu gosod tan yn nes ymlaen.