L1 speakers are relatively easy to gauge, since national censuses would provide sufficiently accurate statistics. Accounting for L2 speakers is very difficult, since there's often little-to-no census-level statistics on the matter, and the definition of proficiency for estimates is difficult to ascertain. Order-of-magnitude estimates are roughly the only level you can do.
On that matter, there are some languages which are clearly much more common (over twice as common) as second languages than native languages. English, French, Malay, and Swahili are obvious candidates for this: English is a common secondary language, well, everywhere; French is common second language in Africa; Swahili in East Africa, and Malay in Malaysia/Indonesia.
On that matter, there are some languages which are clearly much more common (over twice as common) as second languages than native languages. English, French, Malay, and Swahili are obvious candidates for this: English is a common secondary language, well, everywhere; French is common second language in Africa; Swahili in East Africa, and Malay in Malaysia/Indonesia.