The resulting index of labor quality is shown in figure 7, together with that from the TDRI studies. The improvement in education increases the effective labor input by an average of 0.6 percent per year over the 1977-2003 period. The assumption of a 12 percent rate of return would raise the improvement factor to one percent per year. This is in addition to a 2.6 percent annual rate of growth in total employment over the 1977-2004 period. In contrast, the two TDRI studies obtained a 2.8 percent annual rate of quality augmentation over the 1977-96 period.