Garfield I have the same trouble with body fat I am not sure what is correct.
At the gym I was told 22% should be the average for women, I have since also heard 23% and 24% as the average. The following is what the little book I got with my scales says (US info).
Female Underfat Healthy Overfat Obese
20-39 0-21% 21-33% 33-39% 39% and up
40-59 0-23% 23-34% 34-40% 40% and up
60-79 0-24% 24-35% 36-42% 42% and up
Below is another series of definers I have read although these figures seem to be more about how you will look in relation to muscle definition as opposed to what is healthy:
Below Average 26-30%
Improvement Needed 31-40%+
I started at 42%+ and am now reading 27%. So according to the top chart at 38 I am in the 'healthy' range but according to the other I am below average. But overall I am happy with my progress so I will keep doing what I am doing.