How do I plot an exponential average of a 1D array?

I'm capturing a 32,768 point array of data from a digitizer in my PC, and I want to be able to average n number of these arrays with a exponential average. (e.g. if n=30, I would plot the average of the previous 30 arrays of data, and then continue to average excepts now applies a weight to "old" arrays which would gradually tend to zero.) I had this function in an old Lecroy 9350 oscilloscope, and it's referred to there as a "Continuous" Average.

Sorry about the delay, and thanks for the great advice.
I've attached a screenshot here of my block diagram. I have two problems now:
1) there are multiple traces on my plot when there should only by one(see attached screenshot #2)
2) it still doesn't seem to be doing continuous averaging correctly. I'm running this experiment and triggering my scope at 10Hz, but the data I'm seeing plotted is only updating every second or two.In addition, there seems to be no memory of the old shots. Say for example I set the # of averages to 50, and then block the signal to the scope-I don't see the trace gradually trent back to zero. Instead, it immediately drops to zero. Hopefully this all makes sense, and thanks again for the help.
Attachments:
Block Diagram.png ‏77 KB
Front Panel.png ‏112 KB

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