The answer is relatable to how many people drive in a car each day. It simply can't be measured.
They used to be in 120 countries (as of the 90's).
About 6.6 billion, or written as: 6,600,000,000
There are an estimated 6,700 recognized languages in the world. Most of them are spoken by fewer than 1,000 people.
Not all trees are found all over the world. some kinds of trees are found in different places over thee world.