 To get around this problem, the returns to human capital are generally inferred from differences in wages among people with different levels of education.Hall and Jones have calculated from international data that on average that the returns on education are 13.4% per year for first four years of schooling (grades 1–4), 10.1% per year for the next four years (grades 5–8) and 6.8% for each year beyond eight years.Thus someone with 12 years of schooling can be expected to earn, on average, 1.1344 × 1.1014 × 1.0684 = 3.161 times as much as someone with no schooling at all.