Ok, sorry, I was basing my answer about HIPPA in the U.S.
If it’s ok in your country I guess that doesn’t apply.
Myself, I think the easiest approach would be to assign numerical values to the items.
You could use option sets.
Once you’ve assigned numerical values, it would be easier to calculate percentages.
Basing percentages on text data involves breaking the text down and calculating it which is much more detailed.