Grouping Series on 100% stacked bar chart

[ccordner]

I'm trying to track usage over several years, for a Santa's Grotto operation. There are several types of present and what I want is one bar graph, with three 100% stacked columns, showing:

Presents used/remaining this time last year.
Presents used/remaining (based on the number of bookings).
Actual presents used/remaining.

This is to help us track how our present supply is holding out through the season and if we need to order more.

On a related note, is it possible to use formulae for the labels?

So for the columns showing this time last year and the bookings, could I show how the actual difference in presents (more or less) than last year?

Thanks
Chris