period	mm	month
M01	JAN  	January             
M02	FEB  	February            
M03	MAR  	March               
M04	APR  	April               
M05	MAY  	May                 
M06	JUN  	June                
M07	JUL  	July                
M08	AUG  	August              
M09	SEP  	September           
M10	OCT  	October             
M11	NOV  	November            
M12	DEC  	December            
M13	AN AV	Annual Average