According to this article, the number of foreign students enrolled at U.S. universities increased this past year (2013) over seven percent. The total number of international students for the 2012-13 academic year was over 800,000, which is an all-time high.
This demonstrates the continued demand for standardized tests of English ability, such as the TOEFL. The growth was fueled by an increase in students from China (up 21.4%). Chinese students compose the largest group of international students in the U.S., with more than double the amount of the second largest group from India (down 3.5%). Number three is the group from S. Korea (down 2.3%).
The number of students from the Middle East are increasing dramatically, with Saudi Arabia (up 30.5), Iran (up 25.2%) and Kuwait (up 37.4%) all posting large increases. Also the number of students from Brazil grew 20.4%.
In sum, you can expect the demand for TOEFL instruction to continue for the top three nationalities: China, India and S. Korea, plus a surge from students from the Middle East and Brazil.