Avearage in Bex

Dear all,

Month      Value

201501      100

201502      200

201503      300

201504      400

201505      200

201506      100

201507      150

201508      200

201509      300

201510      500

201511      300

201512      400

For example :needs to be calculated in bex.

Avg value calculation (201504)=(201504+201503+201502)/3

                                                 =(400+300+200)/3

                                                 =300

Like wise for all months Avg value needs to be calculated.

Regards,

Linga