The issue of nominal dollars is also significant.  KDP's recent edit summary says, "As new as the movie is - inflation is sufficiently small to have no impact on the figure - so the information is irrelevant."  I think that this completely misses the point of adding that edit.  It is NOT that the AIT numbers would be significantly altered by inflation, but rather that the figures for other documentaries, especially older documentaries, might be.  So it is entirely possible that some older documentary should actually be listed above AIT if inflation adjusted numbers are used.  Your source does not indicate either way, but the most plausible case is that these are simply total gross sales figures regardless of the years in which they were earned.