NPR is the podcasting industry leader, ranking No.1 in audience for all 13 months that Podtrac has measured. In April, NPR attracted 11.357 million listeners for its 36 active podcasts, while This American Life/Serial was No. 2 with 9.45 million listeners for four shows. WNYC Studios, which produced 45 podcasts, was third with 6.76 million, followed by HowStuffWords (3.91 million for 13 podcasts) and Radiotopia (2.98 million for 17 shows). The Moth was the only publisher to crack the top ten with just a single podcast, averaging 1.29 million listeners, which earned it the No. 10 spot.

Podtrack tracks the top 20 podcasts and the top 10 publishers on a monthly basis measured by U.S. Unique Monthly Audience, a.k.a. the number of individual audience members. To be counted, podcast publishers or producers have to use the Podtrack ratings system, but individual podcasts do not. Podtrack says its audience rankings are useful to the podcast industry and advertisers who want to see what shows and publishers attract the largest audiences in a given month.

April’s most-listened-to podcast was This American Life’s self-titled “This American Life,” followed by its sister show “Serial.” WNYC Studios’ “Radiolab” was No. 3, followed by This American Life’s newest entry, “S-Town,” and then WNYC’s “Freakonomics Radio.” NPR boasted seven podcasts in the top 20, including the “TED Radio Hour,” “Fresh Air” and the “NPR Political Podcast.” The New York Times’ daily news headline podcast, “The Daily,” finished April as the No. 13 podcast, and two podcasts that do not subscribe to Podtrac made the list (“The Joe Rogan Experience” and “Pod Save America”).