Again, it's a hard question to answer definitively. The numbers are actually, as I mentioned, quite low overall in terms of how many fatalities there are annually or over a number of years.
There's no doubt that certain fatalities would likely have been prevented. They prevent passengers from being ejected, and so if a passenger died from being ejected, in all likelihood, there's a chance they would have survived, but it's hard to say definitively one way or the other.
Obviously, if they got injured or killed outside of the bus, a seat belt wouldn't do anything on that one.