I actually removed it because my way of calculating the points were rather messy. I might add it in the future again, if I come up with some nice algorithm for calculating points. However, at this moment I am focused on other things. This is open for other people to come up with a suggestion for calculating points - how should upgrades, resources, activity level all factor in on the score?
I would actually say that just the sum of all gold mined should solve the problem. Unless You want to add some bonus for activity. If there is a point, then You can also add other resources to that, but their gold cost for ores would be i it already anyway.
I would suggest adding to refs date of signup, instead of activity a date of last mining and a column with total ref bonus gold for each ref. Also do refs give bonus with other resources as well or just gold ?