Evidently, the post-1997 decline in investment was concentrated in assets with relatively high rates of depreciation (equipment). Depreciation is generally viewed a poor index of capital services because it ignores half of the user cost, the net return to capital.12 Until it is possible to develop more elaborate indexes of capital services, an index based on changes in the net or gross capital stock or a composite of the two seems most reasonable. The remainder of this report uses a composite index with a weight of 75 percent on growth in the gross stock and 25 percent on the net stock.