Selective schools are in low numbers as follows: Birmingham (8), Walsall (2), Wolverhampton (1), Warwickshire (6), Stoke-on-Trent (1), and Telford and Wrekin (2). The highest proportion per head therefore is Warwickshire (its population is between 550,000 and 600,000 people). The other counties and metropolitan boroughs have none, their public education systems are comprehensive in intake. The grammar and independent schools tend to produce pass-rate examination results among the top twenty ranked regionally. Many pupils compete for entrance examinations to attend such long-established Grammar Schools and most have significant parent sponsorship. In 2016 two of the top ten such schools nationally were in Warwickshire, where in the CV37 postal district prices were 34% higher than the county as a whole. The top 20 schools at A-level rarely change from year to year; slightly lower in the table pass-rate boosts and top grades regularly occur among the schools receiving industrial funding, with similar frequency to London, the North East, and the North West, particularly in schools and academies which have some of the most advanced facilities.