Here are some statistics, but not a complete answer to your question.

About 7,600-7,800 enemy aircraft came within AA range of US ships during WWII. Of these, 2,773 were shot down by AA, and another 314 were lost through crashes (suicide crashes) on US ships.

http://www.history.navy.mil/library/online/antiaircraft_action_summary_wwii.htm

The source reckons that 114 US ships were sunk by enemy aircraft in WWII, and 435 damaged (425 of the 549 US ships sunk or damaged were warships, 124 were merchant ships) (143 of the total sunk and damaged by bombs, 51 by torpedoes, 352 by suicide attacks, 3 by strafing).

So, 314 Japanese warplanes were destroyed by crashing into US ships. But, 352 US ships were damaged by kamikaze attacks. (Only explanation is that some of the kamikaze planes were credited as shot down by AA fire, but the wreckage still crashed into a US ship and damaged it).

What these statistics don't tell us is how many of the 2,773 planes shot down by AA fire were planning to carry out a kamikaze attack, how many kamikaze planes were shot down by US air cover. And, crucially, for your question, how many kamikaze planes returned to base after an unsuccessful mission.

You also need to define what you mean by "mortality rate". Do you mean by mission, or over the entire life of the kamikaze airplane?

I guess the only reason a kamikaze bomber should survive is if it flew a mission that did not manage to get into a position from which it could attack a US ship. (Or, getting in such a position, but failing to make the attack.)

Attacking and surviving must have been very rare.