Learned words ratio

As I see, the ratio of learned words to read ones should represent your overall learning efficiency. Still when I look at my stats, I can see very different results for the languages I have been learning.

For Ukrainian which is probably the closest to my native one this coefficient is 6.
For Spanish, which I consider not too hard after learning French in a high school it is 25.
While for Indonesian, which is my main focus now, it reaches a frustrating 66.

Would you consider these results normal? Could it be that besides languages familiarity, other factors play their role?

For example Spanish and Ukrainian have much more forms of the same word than Indonesian. I think hard phonetics or writing system may influence this ratio as well. But I don’t think it applies to these languages, except I feel constant “meng-“ like prefixes in Indonesian makes it harder to remember the word roots.

Does this ratio just measures how you good your memory is, and it is impossible to raise it?