Approximately 98% of the university's 34,000 students are members of the LDS Church, and one-third of its American students come from within the state of Utah. BYU students are required to follow an honor code, which mandates behavior in line with LDS teachings (e.g., academic honesty, adherence to dress and grooming standards, and abstinence from extramarital sex and from the consumption of drugs and alcohol). Many students (78% of men, 10% of women) take a two-year hiatus from their studies at some point to serve as Mormon missionaries. Many BYU students speak foreign languages during their Mormon missions, and approximately 31% of the student body enroll in foreign language courses, making it one of the most multilingual student bodies in the United States. A BYU education is also less expensive than at similar private universities, since "a significant portion" of the cost of operating the university is paid from tithing funds.