He wants to write it like a police procedural, and has been reading novels by the best-selling crime writer Michael Connelly to study the genre.

WSJ: Seth Grahame-Smith: The Master of the Mash-Up

Because they're volunteer-based, and because each state uses different methods to measure reading level, doing a nationwide study would be difficult.

CNN: Learning to read? Try talking to a dog

The global rankings are the result of two studies - the Trends in International Mathematics and Science Study (TIMSS) and the Progress in International Reading Literacy Study (PIRLS).

BBC: Northern Ireland is 'best in Europe' at primary maths

The researchers looked at data on children featured in the British Cohort Study - a large group of people born in April 1970 - to look at the link between reading and maths scores at age 10, and earnings at ages 30, 34 and 38.

BBC: Maths skills add up to higher earnings, study finds