Requests with Round Objects...

If the business requirement persists for a pie or even a gauge then Answers has both of these options.
Pie charts best highlight contributors to a whole, so %-ages are often the best accompanying values. Always showing values forces the pie smaller, think about showing values 'On Mouseover' only or increasing the space (if you have it) occupied by the chart to ensure easy viewing.

From DR. OBI

Stephen Few writes extensively about human desire for all things round, so its not repeated here.