What type of chart/graph do I need?

Use a bar chart with the bars overlapping 100%.

Also add a extra column that calculates the percentage. This can be used as the secondary axis labels and then displayed as data labels.

Plot the 3rd data series on the secondary axis.
Use the Select Data dialog to change 3rd series to use the calculated data as category labels. The plotted data is the Ports avaiable value.

The other 2 series have an overlap value of 100.
You need to use the select data dialog to reverse the plot order so actual data appears infront of the available data.

Add the secondary vertical axis.
for both vertical axis set the Values in reverse order and crosses at Maximum in order for the labels to read top to bottom.

On a separate note if you are using xl2007 files can you update your profile to mention 2007 rather than 2003 as the change in application usage for charts is quite radical between the 2 versions.