The government has used oil revenue for school construction, paying teachers' salaries, and promoting education, including in rural areas. However, maintenance of school structures, as well as teachers' salaries, has been declining. In 2002 the gross primary enrollment rate was 132 percent, and in 2000 the net primary enrollment rate was 78 percent. Gross and net enrollment ratios are based on the number of students formally registered in primary school and therefore do not necessarily reflect actual school attendance. As of 2001, 69 percent of children who started primary school were likely to reach grade 5. Problems in the education system include poor management and planning, lack of oversight, poorly qualified teachers, and overcrowded classrooms.