How does this look to you?
Couldn't have it perfectly the same size for every segment since 190 (the bar's length including two pixels of black on each side) isn't divisible by 9, that might be as good as it gets unless you can make the bar one pixel less wide and still have it work properly.
I highly recommend using .tga over .blp in addons, easier to use and I've had far less problems with it.
Edit: also just noticed I made a small mistake in it; fixed.