For stacked bar charts, Excel 2010 allows you to add data labels only to the individual components of the stacked bar chart. The basic chart function does not allow you to add a total data label that accounts for the sum of the individual components. Fortunately, creating these labels manually is a fairly simply process.
Step 1: Create a sum of your stacked components and add it as an additional data series (this will distort your graph initially)
Step 2: Right click the new data series and select “Change series Chart Type…”
Step 3: Choose one of the simple line charts as your new Chart Type
Step 4: Right click your new line chart and select “Add Data Labels”
Step 5: Right click your new data labels and format them so that their label position is “Above”; also make the labels bold and increase the font size
Step 6: Right click the line, select “Format Data Series”; in the Line Color menu, select “No line”
Step 7: Delete the “Total” data series label within the legend