My best guess would be to create two new calculated fields:

SUM([Confirmed Auto])/(SUM([Confirmed Auto)+SUM([Confirmed Imported]))

and

SUM([Confirmed Imported])/(SUM([Confirmed Auto)+SUM([Confirmed Imported]))

Then use these in the Measure Names card instead.

You are trying to show 2 measures as a percentage of the sum of the 2 measures.

This is not achievable via a built in function of tableau.

You will need to create a calculated field total measure  -->  measure1 + measure 2

then 2 more calculated fields measure 1/ total measure

and measure 2 / total measure

this will give you the percentage values you would like to plot.

If you need further help please share a sample workbook and i can demonstrate the method i described.

That's the correct method Benjamin.

I was just too slow to answer

Keep up the good work.

hey benjamin,

i used your method  and it work fine. i do have one question regarding this method:  how do i show the label of the original value (meaning the one i used to create the calculated field)?

thanks,
natun barosh