Suggestion.
To view history of PNR would it be very much helpful if we can have advanced search option.
Let say if I want to search following together:
1. Train name/no
2. Class of journey....
more... e.g. 1st class, 2nd AC, 3rd AC, SL
3. Final status after chart preparation(WL/RAC/CNF/ALL)
4. Year/Month/date
All of these can provide me the statistics about prediction and it's result. So, based on report one can decide about chances of status after chart-preparation of his current ticket.