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
Its really hard if you compare 2017 to 2018, the disparity of both year's if you bought bitcoin in the highest price then in 2018 market is quite not good absolutely your loss
You can`t compare this and last year by the price. You can`t compare this year price with price from 5 years ago. 5 years ago is interesting date, some people bought bitcoin at 1200 dollars, that was top, next years for them are similar like this year now, after top big drop came. I think that people who bought on top just made a mistake, they didn`t know how things work. They just saw big headlines, price moving up and many thought it will go much higher, well we know what happened. Of course this price is not favorable for this people, but they need to think about that like they learned a hard lesson, there isn`t other way around than to wait now and maybe to buy some more in this dip.