adding chance to a formula

I am using this formula for a population viability analysis: =NORMINV(RAND(),$C$15,$D$15)

How do I change it or add to it so that there is a 1/100 chance that the value is 0? I want the value to be what my original formula is but there is a 1/100 chance that it could also be 0.

Please help!!!

Try

=NORMINV(RANDBETWEEN(0,99)/100,$D$15,$E$15)

Or ?

=IFERROR(NORMINV(RANDBETWEEN(0,99)/100,$D$15,$E$15),0)