Showing relative value of a percentage in a bar chart

[#1]

Hi - I have two values and a date dimension - Invited Renewals and Successful Renewals.  Successful will always be lower than invited, similar to that below:

Date           Invited Renewals  Successful Renewals

Mar  2015          400                    350

Feb  2015          350                     297

Jan   2015          410                    323

I want to be able to show them as a stacked chart - I've been trying to show overlapping, relative, as a percentage, but I can't seem to find something that quite fits.  I've tried to get Successful as a percentage of Invited and show that, but the only way I can seem to be able to it is by taking Successful from Invited, and staking that on top of Successful - This gives me a cumulative amount of correct 'Invites' but obviously the numbers are all wrong when you mouse over - or does a fast change to a table. An image of that version is below: it looks right but its wrong! 

In a perfect world I want to show a bar for  Invited Renewals, but be able to see Successful Renewals as  chunk of that. I cant add it on as a line in a combo, as I am also showing a conversion percentage metric (not shown).  I also don't want to make it a !00% stacked!  On mouseover in the chart below it might say  'Invited Renewals 400   Successful Renewals 350', rather than the current situation, where it says  'Invited Renewals 350 Successful Renewals 50' to get the cumulative figure to be right!

Any ideas?

Cheers

Andrew