I will be honest with you, I do not have any reliable, accurate statistics. However, speaking from experience, I could tell you that, because of the availability of services offered in Quebec, people tend to begin by learning French, because they live in a francophone society. However, that is not enough. They very quickly realize that only speaking one language is a serious handicap, both in Quebec and elsewhere.
English-language learning services are not available in Quebec, that is they are not publicly funded. Our organization offers English-language courses for a fee. They are open to everyone, including immigrants, but people have to pay for them. Obviously, since the offer is not available, people are naturally inclined to take French-language courses, because they are publicly funded.