Hello Mike,
I see that you have featured only the top 100 most common surnames of the year 2001 on here:
https://surnames.behindthename.com/top/lists/belgium (in English)
The Belgian government agency that concerns itself with these kind of statistics has since released the top 10,000 most common surnames of Belgium every year - starting with 2017.
You can download the relevant files below:
https://statbel.fgov.be/en/themes/population/family-names-and-first-names/family-names (in English; just scroll down to the header "Downloads" at the bottom)
All of the files are in .xlsx format, which I am not familiar with. However, they seem to have different names on the Dutch, French and German version of that page, so you might want to compare the files in order to be sure that the numbers are exactly the same across the languages.
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Dutch: https://statbel.fgov.be/nl/themas/bevolking/namen-en-voornamen/familienamen (in Dutch)
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French: https://statbel.fgov.be/fr/themes/population/noms-et-prenoms/noms-de-famille (in French)
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German: https://statbel.fgov.be/de/themen/bevoelkerung/nachnamen-und-vornamen/nachnamen (in German)
That's all - I hope you will be able to use these data! :)
"It is no measure of health to be well-adjusted to a profoundly sick society." ~ Jiddu Krishnamurti (1895-1986)