The latest numbers from Arbitron’s national ratings service shows the medium reaches 90% of 12-17 year olds despite competition from iPods, cell phones and video games.  That’s down from 93% five year ago, but over the last two years teens’ use of radio has actually been trending up.

The on-the-go 18-34 demo has been more troublesome, but even that age group’s consumption rate has stabilized.  The Arbitron numbers show 93% of Hispanics and 92% of African Americans listen each week with roughly the same rate for 18-49 year olds in both groups.

Overall, radio reaches more than 235 million people (12+) over the course of a typical week.  That’s up 3% from five years ago, largely due to overall growth in the population and the inclusion of PPM data into the sample.  Arbitron projects the total reach of radio to grow as more markets replace diaries with electronic measurement.