Initial population of 120 main-belt asteroids with a = 2.1 - 2.4 AU, R = 5 km, regolith covered, eps = 0.9, A = 0.084. Numerical integration for 150 Myr in three groups of 40 asteroids.
Get data, EPS of the decay plot. Evolution of Mars aphelion for R5000m-1, 2, 3 (1 Myr) - looks pretty the same, typical changes from 1.53 AU upto 1.71 AU with periods 0.1 Myr and 2.5 Myr.