Arbitron’s quarterly survey of radio reach in America has found that radio reaches more than 239 million people aged over 12 years old during a typical week, an increase of nearly seven million people compared with a year ago, possibly as a result of various markets moving from diary to electronic measurement.

As more markets convert from diary-based ratings, it appears that cume numbers are growing. Total radio reach is larger than in previous surveys using the diary method. Arbitron says radio reaches 93% of Americans each as measured by its RADAR figures.

The survey company is increasing the sample size of its survey panels with the aim of increasing network radio ratings sample size to 395,000 by the end of the year.