Macroeconomic Measures of Human Capital How exactly do you measure human capital for a given country and what numbers are included in that measure.

The reason why I ask is because im interested in simulating the Mankiw–Romer–Weil version of the solow Model.

Links to where I can get the data will be appreciated.
The approach developed by Barro and Lee has been used in many empirical analysis. They provide a detailed discussion of how to construct an aggregate human capital measure.