Wow, I would not expect different versions of Ubuntu to consume power differently. 5.04 seems best under load, 6.10 best when idle. - Sanjeev Singh

Without error bars, it's difficult to make any conclusions based on this experiment. The numbers like 21.47 look suspicious to me; implicitly they suggest that the error is less than 0.01 Watt, which I don't believe - there are too many factors that affect power consumption. - Igor Krivokon