If you don't like that link - which is just one of the many I got when searching for 'national IQ average' there are many other similar studies to be had. Here's a few of them, again just some results from the first page in my SearXNG instance. The results are not identical but they are comparable.
https://international-iq-test.com/en/test/IQ_by_country
https://www.worlddata.info/iq-by-country.php
https://www.universaliqtest.com/statistics/average-iq-by-cou...
https://www.datapandas.org/ranking/average-iq-by-country
https://www.researchgate.net/publication/229401257_National_...