Some notes about the math involved:

• If you sum the vanilla scrap recycling percentages together, it sums up to only 60%. So scrap is actually 40% air. Further, because it appears that the chances are rolled per potential item when mined, this results in that if you mine scrap, you only get an item around half the time (47%) and can get multiple items per mine.
• Ruins are updated to also yield scrap items, and total expected values are summed. Since ruins also yield items like iron gear wheel in addition to scrap, the mod adds together the expected amount of iron gear wheels from the ruin itself and from the scrap it yields. This results in less deviation in the amount of iron gears from ruins (I might do something about that), as well as fun looking factoriopedia pages.
• The map lists the expected yields of all items instead of showing the total amount of scrap. Since scrap is 1% holmium ore, we can multiply the holmium ore amount by 100 to get the total scrap count. So if an island yields 75k holmium ore, that island has 7.5M scrap.