The relative numeric sizes of things are expressed as a ratio, not a ration.
The survival ratio in a cancer study, for example, tells you what poportion of the patients are still alive at a given later date. Whereas survival rations are the food and drink that an explorer or survivalist or soldier might take with them.
- ratio => verhouding = proportion, fraction, relationship, percentage
- ration => rantsoenen = provisions, deel = allowance, share
Well, there are so many words ending -ion that I for one certainly keep typing it by mistake. But I would never say it!
Prevalence: high. Almost a guaranteed hit.
Frequency: moderate. Not the commonest of words, so it doesn’t come up very often.
Native: no. Apart from typos…
Advanced Dunglish 