is this correct use of possessive apostrophe? just need to check!

[noonar]

is it correct to write:

"He made 2 years' progress with his reading in 6 months."

I think so, as the progress sort of belongs to the months, iyswim!

am i right?

I'd say it should be "year's" but prepared to be corrected by more knowledgable pedants.

You're correct, it's years' as it's plural.

More than one year so I think you're correct!

i was pretty certain i was correct, but am worried that it will look like an error as i think few people would use it correctly in this instance.

(don't want people to think i'm using an apostrophe with a plural... am concerned they won't see it as 'possessive' iykwim)

You are correct, but I agree some people will think you are using an apostrophe with a plural.

You are correct. It is an abbreviation of "two years of progress".

Sorry, I could have put that more elegantly. You are saying he has made "the progress of two years". That construction is analogous to "the field of the animals". The latter would be "the animals' field", so the former is "two years' progress".

you are correct noonar

the years are plural, therefore the ' goes after .