Data on staff employed by the NHS is available from 1979, however due to changes in the classifications of staff only the overall numbers are strictly comparable over time.
Mae data o 1979 ar gael ar gyfer staff a gyflogir gan y GIG; fodd bynnag, yn sgil newidiadau yng nghategorïau’r staff, dim ond y niferoedd cyffredinol y gellid eu cymharu'n union dros amser.