Education in Eritrea is officially compulsory between seven and 13 years of age. However, the education infrastructure is inadequate to meet current needs. Statistics vary at the elementary level, suggesting that between 65 and 70% of school-aged children attend primary school; Approximately 61% attend secondary school. Student-teacher ratios are high: 45 to 1 at the elementary level and 54 to 1 at the secondary level. There are an average 63 students per classroom at the elementary level and 97 per classroom at the secondary level. Learning hours at school are often less than six hours per day. Skill shortages are present at all levels of the education system, and funding for and access to education vary significantly by gender and location. Illiteracy estimates for Eritrea range from around 40% to as high as 70%.