This is based on data gathered in the 2006-2007 reporting year.
The study drew on data gathered in a 1999 national survey of more than 15,000 students.
About 16,000 people visit the branches each day, according to recent data gathered by the agency.
Compiled from data gathered at 18:00 on 2 June 2011.
Compiled from data gathered at 1700 on 7 December 2011.
Compiled from data gathered at 1100 on 13 January 2012.
Compiled from data gathered at 14:30 on 29 July 2010.
Compiled from data gathered at 16:00 on 24 June 2010.
Compiled from data gathered at 1800 on 5 January 2012.
Compiled from data gathered at 15:30 on 22 July 2010.