Usually, I'm looking for rate of change of one item at a time, not all of them at the same time. After that, I'll compare them.
Stacked bar charts, IMO, seem skewed in who gained the most over a period, but not the individual gains. I have no idea what green really ended up with by the end of it because it just kept getting pushed towards the top. I have to constantly go to the left and compare ranges with the previous stack.
Can you recommend an Excel addon/color chooser or website so that persons with normal vision can test their charts and color choices for the four known kinds of color deficients?
It would of cource help you, if the chart lines have different line patterns (dottet lines).
http://colorbrewer2.org has some good palettes for data presentation which they describe as "colorblind safe". I assume this means for all kinds of deficiency.