However as the sample sizes are around 200-500 in each area for those aged 16 to 18 the estimates have been averaged over three rolling years for 16 to 24 year olds.
Fodd bynnag, gan fod maint y samplau tua 200-500 ym mhob ardal ar gyfer pobl ifanc 16 i 18 oed mae’r amcangyfrifon wedi’u cyfartaleddu dros y tair blynedd dreiglol ar gyfer pobl ifanc 16 i 24 oed.