Dear Dipak,
Speaking about the situation of "second" languages in the University of Michigan, we have a general rule for all undergraduate students that they all must learn at least one non-English language for four semesters (2 years). The university teaches 67 languages, including modern and classical languages, and any one of these can satisfy the under-graduate language requirement. The most popular "second" language is Spanish, with something like 3000 students for first and second year Spanish. I could be wrong about the specific number, but it is very high. Within my Department of Asian Languages and Cultures, Chinese and Japanese have enrollments above 500 students. Hindi attracts somewhere near 100 students, while the enrollment for First Year Sanskrit in the upcoming Fall semester is 12.
This refers to the general requirements for all undergraduates. Of course there are specialized departments for modern and classical languages etc. and there are students, graduate and undergraduate, who are studying those languages and cultures as their primary focus. The numbers of students specializing in various languages differ widely.
Madhav Deshpande