Shouldnt be hard to work out for yourself.
You have the staffing levels, the salaries, the monthly ammo used in training, the monthly use of military supplies, gasoline, AF, and the overall monthly cost of military, broken down into def, off and strat.
As the last will show you, it varies a fair bit from month to month.
I would ask why you would want this. But hey, I realise its not for me to put down others ideas, so sorry, guess I'm just playing the Devils advocate.
CC