Netherlands 1972 10 cents

https://en.numista.com/catalogue/pieces734.html
Here, in Numista, this coin is shown in proof until 1970; later years do not have lines for proof coins.
Going recently through my Dutch collection I have discovered a 1972 10c proof (valued at 300$ by NGC)!
Should I add the line? How about other years (1971-1980) that according to NGC proofs exist?

According to my Netherlands catalog, proofsets were made in low numbers until 1972. Exact mintages are not given but with low numbers they really mean LOW (60 ex are mentioned).
Then they reduced the mintages even more drastically for 1973 onwards (how can you reduce drastically if the original mintages were only 60???).
In 1980 they resumed with more normal figures in the tens of thousands...