The 100% stacked column chart lets you graph values in a group. Each value in a group is a stacked column and the total of the stacked columns is always 100%.
The image above shows numbers for 2010,2011 and 2012 grouped for each region. The values are relative to each group meaning you can't compare values for 2010 between, for example, North America and Europe.
I tell you why, the column for 2010 in group North America is bigger than the corresponding column for Europe, however, if you look at the values below the chart you will see that the number is actually larger for Europe than North America.
Why is that? Because the columns are relative in size to each region, not to each year. This makes the chart useful for comparing values to other values in the same stacked column.
Obviously, the chart is pointless if you have many data points in each group making the chart really hard to read.
Build the chart
Select the cell range you want to chart.
Go to tab "Insert" on the ribbon.
Click "100% stacked column" button.
Make the chart easier to read
What can you do to make the chart easier to read? Display the values as data labels on the columns.
Right click on a stacked column
Click "Add Data Labels"
Repeat step 1 and 2 for each column color.
Select the data labels and change the font size and color if needed.
You may need to rearrange values in order to build a 100% stacked column chart.