Calling this a "very popular" name is generous.
There are 3,311 people in the U.S. with the first name Janeth.
Statistically the 3176th most popular first name.
Let's compare it to the much more popular "Janice"
There are 471,786 people in the U.S. with the first name Janice
Statistically the 128th most popular first name.
and "Janet" -
There are 627,392 people in the U.S. with the first name Janet.
Statistically the 89th most popular first name.