Becoming an astronaut is notoriously difficult, with something on the order of 0.01% of all applicants getting picked for the job. To a large extent this is inevitable as only a dozen people per year will get to go to space, while hundreds of millions would potentially like to go. However there's also the component of skill and health - you can't go to space if you're 95 years old, if you have major health issues, if you're not intelligent enough to operate the controls and run the experiments, etc.

Did NASA or other space agencies ever publish estimates of what % of humans could realistically do an astronauts job if given the opportunity? I.e. if NASA was forced to pick the 5000th best candidate instead of the 1st best candidate, would they significantly lower the chance of a successful mission? What about the 50,000th best candidate? By "astronauts job" I'm referring to the most critical parts of the job, not just tagging along as a space tourist. In other words, what percentile of humans could staff the entire space mission without having to sacrifice anything in the process?

Since my previous question was misunderstood, here's an additional example to clarify what I'm thinking of:

1. Imagine we're trying to replace every astronaut on the ISS
2. We need to define what percentile of humans could do the job without harming the expected outcome of the mission (top 0.01%, top 1%, top 10%, etc)
3. What would be the biggest percentile we choose within these constraints? In other words, what percentage of humans could do every single job carried out by ISS astronauts?

Assume that we're willing to provide a reasonable amount of training to the people applying - i.e. if someone isn't familiar with orbital mechanics but has the mental capacity to learn them, we're willing to spend time teaching them the gaps in their knowledge.

Becoming an astronaut is notoriously difficult, with something on the order of 0.01% of all applicants getting picked for the job. To a large extent this is inevitable as only a dozen people per year will get to go to space, while hundreds of millions would potentially like to go. However there's also the component of skill and health - you can't go to space if you're 95 years old, if you have major health issues, if you're not intelligent enough to operate the controls and run the experiments, etc.

Did NASA or other space agencies ever publish estimates of what % of humans could realistically do an astronauts job if given the opportunity? I.e. if NASA was forced to pick the 5000th best candidate instead of the 1st best candidate, would they significantly lower the chance of a successful mission? What about the 50,000th best candidate? By "astronauts job" I'm referring to the most critical parts of the job, not just tagging along as a space tourist. In other words, what percentile of humans could staff the entire space mission without having to sacrifice anything in the process?

Since my previous question was misunderstood, here's an additional example to clarify what I'm thinking of:

1. Imagine we're trying to replace every astronaut on the ISS
2. We need to define what percentile of humans could do the job without harming the expected outcome of the mission (top 0.01%, top 1%, top 10%, etc)
3. What would be the biggest percentile we choose within these constraints? In other words, what percentage of humans could do every single job carried out by ISS astronauts?

Assume that we're willing to provide a reasonable amount of training to the people applying - i.e. if someone isn't familiar with orbital mechanics but has the mental capacity to learn them, we're willing to spend time teaching them the gaps in their knowledge. If someone doesn't know how to operate lab equipment, we're likewise willing to spend a few months showing them the ropes.