As the others have said, their growth rate depends on how much food they have. I havent seen anywhere near the growth stated by the others and where my fry are left in the pond with the adults I would say they would be up to 2" after one year but those would be exceptionally large for that enviroment, the average would be an inch to maybe 1.5".
I have had some fry in a pond on there own and there most reached 2" in the first year. Anything under an inch if healthy would be under 1 year.
I had some that were in a wildlife pond and out of 50 or so I think only 3 or 4 survived but from memory they were big briusers for their age and were between 2 and 2.5" after one year but those would have to have been the fittest of the added fry because the pond was stocked with stickle backs which would have given them stiff competition