Analysis shows that the abundance of a nuclide should be inversely proportional to its cross section for absorbing a neutron averaged over the neutron spectrum present during the s-process. Some uncertainties remain, and they are good targets for new measurements. This process cannot explain all of the isotope ratios observed, and the r-process was developed to solve the problem. This process clearly requires a huge neutron flux, and it is assumed to take place during the explosion of a supernova. An analysis of this process indicates that the relative abundance of each nuclide should be proportional to the decay lifetime of its progenitor on the r-process line.
Theory comes to the rescue.
The same FRDM that gives the calculated nuclear masses can also be used to estimate beta-decay lifetimes. The small magenta squares show the nuclides that are produced when the r-process line decays.