Mesh transition (volume) in a cylinder
 

Hi.
I'm meshing the volume of a cylinder and i have a problem. The tetra sizes should not be uniform in all the cylinder. I need to make a transition, so it must grow the size as the mesh goes to the perifery. Summarizing, in the very interior of the cylinder, the mesh must be more refinated. The problem I have is that the size transition is too abrupt, i need to make it more softly. What configuration should I change?
Thank you very much.