Keep. If the data were not useful then WHO would not be publishing it. While I think we can all agree that the charts do not perfectly represent reality, they do correlate to reality. In other words, we are much better informed with these ball-park estimates than being in the dark completely. Trends and variance therein are just as important as actual numbers, if not more so. It's not up to us as mere wikipedia editors to decide that readers are simply too stupid to find any use in this data.