The number of American students studying abroad increased by 8 percent in the 2006-’07 academic year after rising 8.5 percent the previous year, according to the annual Open Doors report released Monday by the Institute of International Education. The surge of students studying abroad in the past decade has been accompanied by an increase in the number of students receiving academic credit for study abroad, which has risen by almost 150 percent from the 1996-’97 academic year to the 2006-’07 academic year. The number of Yale students studying abroad in the last academic year decreased by 22 percent from the previous year to 141 students.