Data clean up and plot fixes

[Reckless-Satoshi]

Existing plots look great! They have a couple small bugs/issues:

• [x] Volume/contracts per month are aggregated by Months instead of by Month&Year. Therefore plots show the average of those months that have been repeated with an error bar.
• [x] Volume/contracts per month could be ordered chronologically (first bar in Feb 2022, and so on and so forth)
• [x] For timeseries plots, the current date (or last date) is incomplete. The date has not yet finished, therefore it might show a sharp decline on the value at the very end. It is best to drop that value from the dataframe.

[santochibtc]