Why do population trends matter? Because the starting point for any school funding calculation is the number of pupils at a school. A local authority with a falling population will find itself dealing with surplus places. One with an increasing population will need to look at increasing provision.
The map shows the level of occupancy in schools—that is the number of actual pupils as a percentage of the number of pupils a school can admit.
Scroll down for illustrations of overall population trends for Cardiff.
Population by year 1991–2018
Left scale/blue: Cardiff
Right scale/black: Wales

Population by age group and year
Note that the school age population has not risen as sharply as the overall population since 1991. However, the Cardiff population is unusual in Wales in that the 0-15 age group still outnumbers the over 65s.
