According to https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/info/mostused.html
curl -s https://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/info/mostused.html | egrep -i "<LI><SAMP>" | sed -rn "s/.*?<SAMP><a.*?>(.*?)<\/a><\/SAMP>.*/\1/p" | sort | uniq | egrep -iv "\.req" > most_used_apis.spice