3/7 astronauts from observational data are not enough to say anything

Specifically, US Population Ages 55–64 death rate from cardio-vascular disease is 27%. That is roughly 2 out of 7.

Among Apollo astronouts, 3 out of 7 died from CVD. So, that is a difference of one person between matching the overall population and "a significant result." Of course, the difference between 28.5% vs 43% looks huge, but that is just one person.

These people would have flunked my Intro Stats class for using percentages with tiny samples.