number of replies since last thread visit

[covort]

Basically i want to change my forum to say the amount of replies since last visit of the thread, / total replies

If not visited to the thread before it would show a * or the entire amount. an example:
*/100
13/50 (13 new replies since last visit / 50 total replies)

i can pay $5, if that will bump the interest in getting this up

 

[covort]

Guys i'm willing to bump this to $20 if someone can get this for me