D performance share fell from 72 to 68 percent over the same period. D activities is shifting. Applied research grew from 22 to 25 percent, and basic research increased from 13 to 16 percent. D activities may make these conceptual distinctions less useful in the current research environment than they had been previously. D total was about 12 percent in 1985.
D performance is highly concentrated and relatively stable.
D carried out in 10 States accounted for 67 percent of the 1991 U.S. expenditure total. California alone accounted for a 20-percent share.