with 1992 is due primarily to federal income tax recoveries of $294 million offset by a decrease of approximately $96 million in investment income received. CNA believes that future liquidity needs will be met primarily from operations. Additional sources of cash flow include sales and maturities of investments, and financing activities. CNA's debt position in relation to total capital is low which allowed it to take advantage of the current borrowing opportunities at favorable rates in the capital markets. As a result, on October 25, 1993, CNA filed a shelf registration statement with the Securities and Exchange Commission which made $900 million of debt securities available for issuance from time to time. In addition $100 million from a previous shelf registration remained available for issuance. In November 1993, CNA sold $250 million principal amount of 6.3% notes, due 2003, and $250 million principal amount of 7.3% debentures, due 2023, at an effective rate per annum of 6.4% and 7.3%, respectively. CNA contributed $475 million of the proceeds from this offering to the capital of Casualty. An additional $500 million of debt securities and/or preferred stock remains available for issuance under the shelf registration statement. Net cash flows are invested in marketable securities. Investment strategies employed by CNA's insurance subsidiaries consider the cash flow requirements of the insurance products sold and the tax attributes of the various types of marketable investments.
Revenues increased by $70.5 and $223.7 million, as compared to 1992 and 1991, respectively. Net loss decreased by $34.6 million and increased by $5.4 million, as compared to 1992 and 1991, respectively. Revenues increased and net loss declined, as compared to 1992, due to Gulf of Mexico jackup rigs achieving nearly 98% utilization due to higher natural gas prices and deployment to Mexico of jackup rigs under long term contracts. This caused revenues and operating income to increase by approximately $38 million as compared to 1992. Since this recovery, a number of jackup rigs have been mobilized to the Gulf of Mexico from foreign locations. To date, the market has been able to absorb this increase in supply but Diamond Offshore faces a risk that rates and utilization can decline if the number of rigs available exceeds demand. This risk is magnified since most Gulf of Mexico employment is short term, on a well to well basis. Higher rig utilization and day rates in the Gulf of Mexico were partially offset by adverse market conditions in the North Sea due primarily to changes in the United Kingdom Petroleum Revenue Tax. In addition, regulatory changes will require substantial capital expenditures for older rigs in order to obtain licensing for
SFAS No. 107, "Disclosures about Fair Value of Financial Instruments," requires disclosure of fair value information whether or not recognized in the balance sheet, for which it is practicable to estimate that value. In cases where quoted market prices are not available, fair values may be based on estimates using present value or other valuation techniques. These techniques are significantly affected by the assumptions used, including the discount rates and estimates of future cash flows. Accordingly, the estimates presented herein are subjective in nature and are not necessarily indicative of the amounts that the Company could realize in a current market exchange. SFAS No. 107 excludes certain financial instruments and all nonfinancial instruments such as real estate and insurance reserves from fair value disclosure. Thus, the aggregate fair value amounts cannot be summed to determine the underlying economic value of the Company. The carrying amounts and estimated fair values of the Company's financial instruments are as follows:
Reserves--In the fourth quarter of 1992, Continental increased its reserve with respect to potential exposure to asbestos-related bodily injury cases by $1.5 billion. In connection with the agreement in principle announced on August 27, 1993, Continental determined to add $500 million to such claim reserve. The Fibreboard litigation represents the major portion of Continental's asbestos- related claim exposure. There are inherent uncertainties in establishing a reserve for complex litigation of this type. Courts have tended to impose joint and several liability, and because the number of manufacturers who remain potentially liable for asbestos-related injuries has diminished on account of bankruptcies, as has the potential number of insurers due to operation of policy limits, the liability of the remaining defendants is difficult to estimate. Further, a recent trend by courts to consolidate like cases into mass tort trials limits the discovery ability of insurers, generally does not allow for individual claim adjudication, restricts the identification of appropriate allocation methods and thereby results in an increasing likelihood for fraud and disproportionate and potentially excessive judgments. Additionally, management believes that recent court decisions would appear to be based on social of other considerations irrespective of the facts and legal issues involved. The Global Settlement and the Trilateral Agreement are subject to court approval. There is limited precedent with settlements which determine the rights of future claimants to seek relief. It is extremely difficult to assess the magnitude of Continental's potential liability in respect of such future claimants if the Global Settlement and the Trilateral Agreement are not approved and upheld, keeping in mind that Continental's potential liability is limited to persons exposed to asbestos prior to the termination of the policy in 1959. Projections by experts of future trends differ widely, based upon different assumptions with respect to a host of complex variables. Some recently published studies, not specifically related to Fibreboard, conclude that the number of future asbestos-related bodily injury claims against asbestos manufacturers could be several times the number of claims brought to date. Such studies include claims asserted against asbestos manufacturers for all years, including claims filed or projected to be filed in respect of periods after 1959. As indicated above Continental, Fibreboard and plaintiff attorneys have reached settlements with respect to approximately 95,000 claims, subject to the resolution of coverage issues. Such amount does not include presently pending or unsettled claims, previously dismissed or claims settled pursuant to agreements to which Continental is not a party. Another aspect of the complexity in establishing a reserve arises from the widely disparate values that have been ascribed to claims by courts and in the context of settlements. Under the terms of a settlement reached with plaintiff counsel in August 1993, the expected settlement for approximately 34,000 claims for exposure to asbestos prior to 1959 is expected to be $445 million, or an average of $13,000 per claim. Based on reports by Fibreboard, since September 1988, Fibreboard resolved approximately 40,000 claims (other than by the assignment process noted above), approximately 45% of which involved no cost to Fibreboard other than defense costs, with the remaining claims involving the payment of approximately $11,000 per claim. On the other hand, a trial court in Texas in 1990 rendered a verdict in which Fibreboard's liability in respect of 2,300 claims was found to be approximately $310,000 per claim including interest and punitive damages. Fibreboard entered into a settlement of such claims by means of an assignment of its potential proceeds from its policy with Continental. Continental intervened and settled these claims in 1992 for approximately $77,000 on average, subject to resolution of the coverage appeal. Continental believes that as a result of the proposed Global Settlement and the Trilateral Agreement it has greatly reduced the uncertainty of its exposure with respect to the Fibreboard matter. However, if neither the Global Settlement nor the Trilateral Agreement are approved and upheld, in light of the factors discussed herein, the range of Continental's potential liability cannot be meaningfully estimated and there can be no assurance that the reserves established would be sufficient to pay all amounts which ultimately could become payable in respect of asbestos-related bodily injury liabilities. While it is possible that the ultimate outcome of this matter could have a material adverse impact on the equity of CNA, management does not believe that a further loss material to equity is probable. Management will continue to monitor the potential liabilities with respect to asbestos-related bodily injury claims and will make adjustments to the claim reserves if warranted.