Set up a Bar Graph with interchangable variables

Hi All,
Don't know how clear the title for this thread is , but...

I have been asked to set up a graph depicting known staff abstractions over a given period e.g. annual leave, people working out of office, measured against minimum staffing requirements.
In addition I want some command buttons built in that will alter the outcome of the graph by a given percentage to allow for the forcasting of future abstractions.
Working on the principal that a picture speaks a thousand words I have attached a mock up of what I am trying to achieve.
Any suggestions would be very welcome!
Keith