It can be challenging to determine the number of individuals who speak English as a second language.
There are a few reasons for this.
1. When is a person considered a second language speaker? What level of English proficiency is required? Is it sufficient to be able to engage in simple conversations? Or does the individual need to be able to read and comprehend books in that language? There is no consensus on these questions.
2. In some countries, linguists have conducted thorough sociolinguistic studies and have compiled data on the number of English language speakers. In other countries, however, such data is not readily available. In his book „The Cambridge Encyclopedia of the English Language,“ linguist David Crystal arrived at estimates based on the percentage of individuals over the age of 25 who have completed secondary education and are expected to have a certain level of English proficiency.