Realistic allocation of annual trade data to monthly based on seasonal patterns.

[kellynm]

Is your feature request related to a problem? Please describe.
Right now, we allocate annual $ value evenly across 12 months and do not consider possible seasonal fluctuations in trade.

Describe the solution you'd like
Analyze available monthly data per country and quantify relative changes in trade $ per month. Allocate annual $ values using same pattern. Should look at this per country and take average trend over many years.

Describe alternatives you've considered
This may not be necessary considering the level of precision of the model (broad scale, not finely tuned, generally looking at annual trends vs monthly).