While the cost of these efforts has been borne by the increasingly environmentally conscious petroleum industry, the expenditures are relatively small considering the immense profits enjoyed by that industry - estimated to be over $41 billion in the years 1967-1983 according to a report by the Alaska State Department of Revenue. For further analysis, see: Natural Resources Defense Council et al., Tracking Arctic Oil: The Environmental Price of Drilling the Arctic National Wildlife Refuge, (New York: Natural Resources Defense Council, 1991); "Super Profits Keep Oil in the Pipeline," Alaska Conservation Foundation, Dispatch, [Winter, 1993]; and "Richard A. Fineberg, "Alaska North Slope Oil Profits and Proposed Environmental Mitigation Measures," Paper presented at the 15th Annual North American Conference of the International Association for Energy Economics, Seattle, WA [Oct, 1993].