Literacy is equally poor:
[https://literacytrust.org.uk/information/what-is-literacy/]
England : 1 in 7 (14.9% / 5.1 million people) adults in England lack basic literacy skills.
Scotland : 1 in 4 (26.7% / 931,000 people) adults in Scotland experience challenges due to their lack of literacy skills.
Wales: 1 in 8 (12% / 216,000 people) adults in Wales lack basic literacy skills.
Northern Ireland: 1 in 5 (17.9% / 550,000 people) adults in Northern Ireland lack basic literacy skills.
www.nationalnumeracy.org.uk/what-issue
You'll have to open the link as it's a graph, between 2003 and 2011, the numeracy rate has dropped from 26% to 22% of the adult population.