Its possible to calculate an average weighted price for any duration of time be it this year or last or a rolling 12 month.    This measure could be known as volume weighted average price or vwap, its far more common to use just simple moving average of price regardless of volume but adding the amounts traded at every price increases accuracy.

Problem with BTC is that it has no one exchange so is very hard to decide on exactly, hence ETF regulators indecision.    Its likely december was volume heavy but not so much that the past months have not exceeded it by now, we have more holders around this price then above imo