I have Monthly IMF Trade Data.
exporter importer timeperiod exports
ARG USA 1990M1 12451011
ARG USA 1991M2 54215781
ARG UK 1990M10 5471122
USA ALB 2000M11 987335
and so on...

How can I change the timeperiod from 1990M1, 1990M2, etc to January 1990, February 1990, etc.