The percentage of compensations to actual vaccines administered is 0.003%. Three one-THOUSANDTHS of one percent of cases of vaccination have resulted in compensation for injury.
If this is 3256/87.4M, I get 0.0037%, but I'll asume this is how the figure was calculated. This is then the number of compensated claims over so many years divided by the number of children receiving vaccines.
So the probability of a child getting getting a compensated vaccine injury (IF only kids got vaccines) would be 0.000037.
I don’t know about you, but a safety rating of 99.997% seems really great to me!
Nope, this doesn't seem great. That's also 1/27027, which is much higher than 1 in a million that is quoted. (How much higher? About 35 times higher.)
Additionally, the NVICP claims are not limited to children, and the above calculations are by person, not by injection, so the actual safety rate is significantly higher than 99.997%. If you included all adult vaccinations, and counted number of injections rather than number of vaccinated persons, you’d get something that probably looks like 99.9999999999999999% of child and adult vaccinations resulting in no serious adverse events.
Where did all those decimals come from? That's not how estimates work. Kids are about 25% of the population, but they take most vaccines, except for the flu shot, which in contrast, is taken by some adult every year. This complicates the numbers, but let's estimate the average person takes 50 vaccines in their lifetime, half of those as kids. So we can divide by two. That's it. Not even an order of magnitude, much less 12 or however many that was. Also adults have only been taking so many vaccines recently. Most vaccines, dose wise, have been taken by children with the new vaccine schedule. On the other hand, the CDC says only 10% of events are reported to VAERS, so let's consider this a wash.
counted number of injections rather than number of vaccinated persons
You're either calculating the rate per person, as done above, or the rate per injection. The rate of injury per person was already approximated as 0.000037.
The rate of injury per dose would divide by the average number of doses per person. If you say this is about 35, then you recover the 1 in a million probability. This is per dose.