At the national level the balance of primary incomes makes gross income, i.e. before deduction of consumption of fixed capital, equal to Gross National Income (GNI).

UNESCO: Belarus: Report: Part I: Descriptive Section

By contrast, Americans overall reported less than 10% of their adjusted gross income as coming from capital gains.

FORBES: Taxes

The richest 400 reported 1.3% of all adjusted gross income but booked 8.5% of all net capital gains.

FORBES: Taxes

If your adjusted gross income next year is lower than the threshold for the additional Medicare tax levels, your capital gains rate for 2013 might only be 20% (and it could even remain at 15%, depending on how the new rules end up after negotiations).

FORBES: Sell Stock by Year-end for Tax Reasons? Think Twice