If you are about to donate/destroy some tokens, it's recommended that you refresh your KillProof profile first so that we get the maximum number of tokens you had. Make sure you refresh your tokens again before doing any more raiding so that we then get the minimum number as well and any new ones you get are counted as new.
Coffer totals are just the current value - older totals are not kept.
Technical: We calculate the minimum number (minValue) someone is likely to have had based on their historical values going back to the later of their KillProof.me signup date or the end of May 2019. For each value, if it's more than the previous value, we add the difference to minValue since they have gained tokens. If someone donates some tokens for guild decorations or destroys them, the previous value will be higher and we ignore the difference (we could track it to show how many have been donated/destroyed).