How to know the player have fast Training?

Hello guys, I wonder how to know/choose the player that have ability of fast in training. . As I know that young player big chance to have fast ability in training. But when I bought some young players like 18-22 yo, not all of them have fast ability in training.
So, how you guys choose right player and make sure that player can produce many skill points in training.
Thanks guys:D

Look at his price (market value). Higher market value means more training potential.

I always choose players who are about 18-19 y.o and their value is about above 10M (at my level 5 and 6). Their training speed are very fast (+145 each in Hard #3)

Hmm. Thanks you all. . .
all this time, I only choose player from rating and age. lol
I didnt realise about the price