The article
https://en.numista.com/catalogue/pieces7697.html
in mintage section gives
1985 12 500 23% anvil
Note. Obviously the percentage is from wrongly described occurrence of lines and has nothing to do with frequency as it expected to be. This is not the case of this topic and in this post onwards this nonsense will be omitted.
1. There is no statement about mint sets issue, as for example in https://en.numista.com/catalogue/pieces2174.html
where the mint sets are described separately.
2. The mint sets mintage is given in the Standard Catalog of World Coins as KM#MS9. It presents mintage 24000 pcs.
So the article states that there were 12500 pcs coins out of which only 24000 were packed in mint set.
A proofreading is required.