Nobody has done a proper study, but it is commonly believed that Kaharwaa taal is by far the commonest taal used in Hindi film songs. In the 30s it was different. Here is Alison Arnold in her doctoral thesis (1991).
She probably had access to only about 80 songs of the thirties. I have about 1,260 songs. This exercise should be done again. I am sure a paper based on it can be published in a reputable journal. If somebody volunteers, I will be happy to send all these songs.
Now you know!