The Modern Language Association of America has an interesting page on their Web site that lets you find out the number, ages, and percentage of speakers of each language in a particular geographic region. Here is some information from the site about the Modern Language Association of America:
Founded in 1883, the Modern Language Association of America provides opportunities for its members to share their scholarly findings and teaching experiences with colleagues and to discuss trends in the academy. MLA members host an annual convention and other meetings, work with related organizations, and sustain one of the finest publishing programs in the humanities. For over a hundred years, members have worked to strengthen the study and teaching of language and literature.