* Different Sign Languages: Each country generally has its own unique sign language, and there is no universal sign language.
* Deaf Population: The number of deaf people in a country is a key factor, but it's hard to get accurate numbers for all countries.
* Sign Language Recognition: Some countries may have more official recognition of sign language, making it more widely used.
* Cultural Factors: The use of sign language can vary significantly based on cultural norms and attitudes towards deafness.
Therefore, it's not possible to answer your question definitively. It's important to note that sign language is a vital form of communication for deaf communities worldwide, and its use is growing and evolving in many countries.