the specification you really need to look at is the passband insertion loss of 4.5 dB maximum.
your system design had better be able to handle 4.5 dB insertion loss, or else find a better filter!
typical means if you took 20 filters out of a huge mixed up bin of these filters, containing various manufacturing date codes, you would probably average out at a 3.1 dB insersion loss.
the measured data on ONE filter, is almost meaningless. it is way better than a more typical one they will ship you. i think they publish it just to give you and idea of the rolloff with frequency without people bothering them by calling up.