This weekend on The iHeartRadio Countdown Mario is out of town so good friend of the show Gavin DeGraw is stepping by to countdown the top 20 songs in the land! Gavin is currently working on new music, doing some touring AND hosting a new iHeartRadio Podcast called 'How Men Think' which you can check out right here. Big thanks to Gavin for coming down to the studio and hosting. He'll be counting down the top 20, playing some throwback classics, playing some of his songs and much more! Tune in!