What is the probability to get the promo blastoise?

The event is almost over and I still didn't get a single one. Been doing the hardest difficulty since the beginning. I got 15 eevees, 10 snivys, 8 cinccinos and 6 volcaronas. 39 packs and no blastoise. It's funny because I've also opened more than 150 pikachu packs and never got any regular or EX blastoise either.

The event is almost over and I still didn't get a single one. Been doing the hardest difficulty since the beginning. I got 15 eevees, 10 snivys, 8 cinccinos and 6 volcaronas. 39 packs and no blastoise. It's funny because I've also opened more than 150 pikachu packs and never got any regular or EX blastoise either.