Distributed weightage constraint

In reply to dave_59:

The program was with 6 iterations. If i increase the samples, weighted distribution works better.

The example posted can be considered as a testcase, that is required to cover 3 sets.
So i defined the testcase to randomize 2*(number of sets)times.

If i consider randc,
randc bit [2:0] cnt;
“cnt” is guaranteed to have different randomized value, and 1 testcase with 8 iterations of randomization is going to cover all the possibilities.

Using weighted distribution, How do we come up with a similar figure?