If you do a search on this forum for "running average" you should find some useful info as this topic has come up.
http://forums.ni.com/ni/board/message?board.id=170&message.id=5008&requireLogin=False
http://forums.ni.com/ni/board/message?board.id=140&message.id=8505&requireLogin=False
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3EA9756A4E034080020E74861
This last one looks like one of the examples you will see in the LabVIEW "Help/Find Examples" keyword 'average'
Good Luck
P.M.
PutnamCertified LabVIEW Developer
Senior Test Engineer North Shore Technology, Inc.
Currently using LV 2012-LabVIEW 2018, RT8.5

LabVIEW Champion