How consistent has the ACT been really?

So let’s say for the sake of discussion that I took the ACT and got a 34. If I were to go back in time and take the ACT in 2000 or so, would I really get a 34 (or close)? What about it was the other way around (took ACT in 2000 and got 34 and jumped time)? I know this is what ACT really strives for, but in practice is this accurate?

You would probably get a 34 or a 35 because the test has gotten harder over the years now that more competitive people are taking it over the SAT. The english, science, and reading sections would be easier but the topics on the math section would seem a little harder because, although limited in scope, the questions required more creative thinking.