Paix Liturgique, the French organisation that campaigns for the traditional Mass has published an interview with Christian Marquant, in which he describes some research that he has conducted into vocations for the traditional priesthood.
You should go to the website of Paix Liturgique to find the details, but here is a summary of how these vocations are distributed across the world. The figures relate to the numbers of young men who are taking part in some form of Propaedeutic year or formal preliminary year in preparation for entering a seminary.
United States 57
Dominican Republic 3
Czech Republic 2
Costa Rica 1
Congo Brazaville 1
Congo Kinshassa 1
New Zealand 1
Christian Marquant points out that his research is not complete, and may contain some errors. Also, There is no guarantee that all these candidates will become ordained priests.
Nevertheless, it indicates the geographical spread of interest in the Traditional Mass, even in countries where it is currently not available.