FC standings?

When the weekly and monthly FC standings are calculated, is it based on the total FC credits held at the time of calculation or how many credits were obtained during that week or that month? I haven't really paid attention to how it worked before but now that I'm running an FC I feel I should know.

I always thought it was the number of company credits earned that week/month. Someone correct me if I'm wrong?

Amount earned in that time period, not amount currently held.

Thank you.