This is hard to achieve when, as is now the case in many big firms, a large proportion of staff are temporary contractors.

The Newsweek list of top U.S. high schools was made this year, as in years past, according to a single metric, the proportion of students taking college-level exams.

As mass production techniques were refined in the 19th century, the price of pianos dropped to the point that a larger proportion of the population could afford to own them.