There was a similar decrease for three to four year olds, decreasing from 23.3% in 2011 to 18.2% in 2021, a 5.2 percentage point decrease.
Roedd gostyngiad tebyg ar gyfer y boblogaeth tair i bedair oed, o 23.3% yn 2011 i 18.2% yn 2021, gostyngiad o 5.2 pwynt canran.