@Override
    public String getSortableSection(@NonNull final Geocache cache) {
        final int finds = cache.getFindsCount();
        return 0 == finds ? "--" : String.format(Locale.getDefault(), "%.2f", ((float) cache.getFavoritePoints()) / finds);
    }
sorts caches by popularity ratio (favorites per find in %).
main/src/main/java/cgeo/geocaching/sorting/PopularityRatioComparator.java