that percentage indicates the number of correct PNR for that particular train and your accuracy.
So suppose a member X has predicted 15 times for a train, say A and has had 12 correct predictions.
So when member X will predict 16th time for the same train, in fron of his name it will show 15 corr pred (80% accuracy).
You are new and...
more... havent predicted for many trains, hence blank indicating its your first predictions.
For those trains you have already predicted, when you predict again it won't show blank.