In astronomy I&#x27;ve always heard the rule of 10s.<p>10% of astronomers get the PhD, 10% of the PhDs get post docs, 10% of post docs get tenure.<p>And tenure in 0-2 years? That&#x27;s impossible outside of China or India or the Soviet bloc. I think the average amount of time an Astronomer spends in post-docs is 9-12 years.