The 10-percent sample showed that approximately three-fourths of the labor force worked in the agricultural sector. According to the National Bureau of Statistics, in the mid-1980s more than 120 million people worked in the nonagricultural sector. The sample revealed that men occupied the great majority of leadership positions. The average worker was about thirty years old, and three out of every four workers were under forty-five years of age. The working population had a low education level. Less than 40 percent of the labor force had more than a primary school education, and 30 percent were illiterate or semiliterate.