Re: @ wolfetone
"Just as 50% of schools will be below average no matter what we do".
I accept your sentiment, but the statement is incorrect. If I have 4 gifts priced at £1, £9, £9 and £9, 75% are below (cost more than) the average of £7, while 25% are (is) above. Conversely, if they are £1, £1, £1 and £9, 75% are above (cost less than) the average of £3, while only 25% below.
As always, it depends what you are measuring and how it is being reported. There will, however, always be at least one school below some specified average - unless all are equal.