IHeartRadio Countdown

iHeartRadio Countdown is a globally-syndicated, independent song countdown radio program. The countdown is based on the popular iHeartRadio, an Internet radio platform owned by iHeartMedia, Inc. (formerly Clear Channel Broadcasting, Inc.) The show premiered on January 14, 2014 on selected iHeartMedia-owned stations, and is syndicated by Premiere Networks. And Australian Radio Network in Australia. 
As of 2018, the iHeartRadio Countdown is currently aired in two editions: the CHR edition (hosted by KIIS-FM’s JoJo Wright since 2018; previously it was hosted by Romeo since its launch) and the Hot AC edition (hosted by Mario Lopez).
Top Songs of the Year.
On December 26, 2013, iHeartRadio launched a similar "Top Songs of the Year" which was broadcast on Clear Channel-owned CHR stations (such as Z100 New York, KIIS-FM Los Angeles, etc.) in comply to those stations' year end charts from the previous years, usually before New Year's Day. From 2014-2017, the top 100 songs were counted down, but after JoJo Wright took over as host in 2018 it was reduced to 50 songs. The No. 1 songs each year (beginning with the launch year, 2013) are:
International versions.
In Australia, selected KIIS stations airing the local version of the same name. But unlike the U.S. version of the chart, the top 20 songs from both international and Australian acts were aired. It is hosted by KIIS 106.5 Sydney host Kian.
In New Zealand, ZM also airs the local version of the show (entitled "ZM's iHeartRadio Official Countdown"), bringing the top 40 songs on the chart. The show broadcasts every Saturday from 2pm to 5pm on all ZM stations nationwide, and is hosted by Cam.
in Canada, iHeartRadio Launched a similar program called "iHeartRadio Top 20", Airs Weekends on Canadian Orbyt Media Affiliated stations in two languages. English is Hosted by Andrea Collins from Toronto and French is hosted by Patrick Langlois From Montreal.