After-tax earnings of our business operations in 2018 were favorably affected by lower U.S. income tax expense, primarily attributable to a reduction in the statutory U.S. corporate income tax rate from 35% to 21%. The effect of the lower U.S. statutory income tax rate in 2018 on the comparative after-tax earnings of our various business operations varied, reflecting the differences in the mix of earnings subject to income tax, income tax credits and the effects of state and local income taxes.
The timing and amount of catastrophe losses can produce significant volatility in our periodic underwriting results, particularly with respect to our reinsurance businesses. Generally, we consider catastrophe losses in excess of $100 million (pre-tax) from a current year event as significant. We incurred estimated pre-tax losses of approximately $1.6 billion in 2018 and $3.0 billion in 2017 from significant catastrophe events.
Property/casualty premiums earned in 2018 were $8.9 billion, an increase of 18.2% compared to 2017, while premiums earned in 2017 increased 4.6% compared to 2016. These increases were primarily attributable to higher direct and broker markets business, derived primarily from new business and increased participations for renewal business in both property and casualty lines. Premiums earned included approximately $1.8 billion in both 2018 and 2017 and $1.7 billion in 2016 from a 10-year, 20% quota-share contract entered into by NICO with Insurance Australia Group Limited, which expires in 2025.
Pre-tax interest and other investment income increased $588 million (46.6%) compared to 2017. The increase reflected the effect of higher short-term interest rates in 2018 and higher other investment income, partly offset by lower interest from lower average investments in fixed maturity securities. Our invested assets continue to include significant levels of short-term investments. We believe that maintaining ample liquidity is paramount and we insist on safety over yield with respect to such investments. Dividend income increased $60 million (1.7%) in 2018 as compared to 2017, reflecting the impact of increased investments in marketable equity securities and higher dividend rates, partially offset by Restaurant Brands International’s redemption of our $3 billion investment in 9% preferred stock in December 2017.
BNSF’s revenues were $21.4 billion in 2017, representing an increase of $1.6 billion (7.9%) versus 2016. Pre-tax earnings increased 11.2% in 2017 compared to 2016. During 2017, BNSF’s revenues reflected a 2.4% comparative increase in average revenue per car/unit and a 5.3% increase in volume. Combined volume was 10.3 million cars/units in 2017 compared to 9.8 million in 2016. The increase in average revenue per car/unit was primarily attributable to higher fuel surcharge revenue, increased rates per car/unit and business mix changes.
After-tax equity method earnings includes Berkshire’s share of earnings attributable to Kraft Heinz, Pilot Flying J, Berkadia and Electric Transmission of Texas. Our after-tax equity method losses in 2018 included approximately $2.7 billion from intangible asset impairment charges recorded by Kraft Heinz. Our after-tax equity method earnings in 2017 excluded approximately $1.1 billion from the net effects of the TCJA on Kraft Heinz’s net earnings. Corporate interest and dividend income in 2016 included pre-tax dividend income of $180 million from our Kraft Heinz preferred stock investment, which Kraft Heinz redeemed in June 2016.
After-tax other earnings (losses) also include charges arising from the application of the acquisition method in connection with certain of Berkshire’s past business acquisitions. Such charges were primarily from the amortization or impairment of intangible assets recorded in connection with those business acquisitions.
Certain accounting policies require us to make estimates and judgments in determining the amounts reflected in the Consolidated Financial Statements. Such estimates and judgments necessarily involve varying, and possibly significant, degrees of uncertainty. Accordingly, certain amounts currently recorded in the financial statements will likely be adjusted in the future based on new available information and changes in other facts and circumstances. A discussion of our principal accounting policies that required the application of significant judgments as of December 31, 2018 follows.
GEICO predominantly writes private passenger auto insurance. As of December 31, 2018, GEICO’s gross unpaid losses were $19.5 billion. Claim liabilities, net of reinsurance recoverable were $18.6 billion.
We test the adequacy of the aggregate claim liabilities using one or more actuarial projections based on claim closure models, and paid and incurred loss triangles. Each type of projection analyzes loss occurrence data for claims occurring in a given period and projects the ultimate cost.
We record additions to property, plant and equipment used in operations at cost, which includes asset additions, improvements and betterments. With respect to constructed assets, all materials, direct labor and contract services as well as certain indirect costs are capitalized. Indirect costs include interest over the construction period. With respect to constructed assets of our utility and energy subsidiaries that are subject to authoritative guidance for regulated operations, capitalized costs also include an equity allowance for funds used during construction, which represents the cost of equity funds used to finance the construction of the regulated facilities. See Note 1(t).
Other service revenues derive from contracts with customers in which performance obligations are satisfied over time, where customers receive and consume benefits as we perform the services, or at a point in time when the services are provided. Other service revenues primarily derive from real estate brokerage, automotive repair, aircraft management, aviation training, franchising and news distribution services.
We are party to contracts where we are the lessee and other contracts where we are the lessor. For contracts where we are the lessee, our consolidated assets and liabilities increased by approximately $6 billion as of January 1, 2019, primarily due to the recognition of right-of-use assets and lease liabilities with respect to operating leases. We do not believe the adoption of ASC 842 will have a material effect on our consolidated financial position, results of operations or cash flows.
In June 2016, the FASB issued ASU 2016-13 “Financial Instruments-Credit Losses,” which provides for the recognition and measurement at the reporting date of all expected credit losses for financial assets held at amortized cost and for available-for-sale debt securities. Currently, credit losses are recognized and measured when such losses become probable based on the prevailing facts and circumstances. ASU 2016-13 is effective for reporting periods beginning after December 15, 2019. We are currently evaluating the effect this standard will have on our Consolidated Financial Statements.
Net gains from equity securities in 2017 included approximately $1.0 billion related to the surrender of substantially all of our BAC Preferred as described in Note 4. Gross gains from equity securities in 2016 included approximately $4.2 billion from the redemptions of our investments in Wm. Wrigley Jr. Company and Kraft Heinz preferred stock and from the sale of Dow Chemical Company common stock received in the conversion of our Dow Chemical preferred stock investment. In 2016, we also recorded a non-cash holding gain of approximately $1.1 billion from the exchange of P&G common stock in connection with the acquisition of Duracell. See Note 2.
The equity index put option contracts are European style options written prior to March 2008 on four major equity indexes. The remaining contracts expire between April 2019 and October 2025. At December 31, 2018, the remaining weighted average life of all contracts was approximately 1.9 years. In 2018, one equity index put option contract expired and another contract was terminated by mutual agreement with the counterparty. These contracts had an aggregate notional value of approximately $1.2 billion. Contracts with notional values of $12.2 billion will expire in 2019.
In the fourth quarter of 2017, we increased our estimated ultimate claim liabilities under the aforementioned AIG contract by approximately $1.8 billion based on higher than expected loss payments reported by AIG under the contractual retention. We also increased the related deferred charge asset by $1.7 billion based on our re-estimation of the amounts and timing of future claim payments. The estimated ultimate claim liabilities with respect to the AIG contract were approximately $18.2 billion at December 31, 2018 and at December 31, 2017 and the related deferred charge assets were approximately $6.9 billion at December 31, 2018 and $7.5 billion at December 31, 2017.
Borrowings of BHFC, a wholly owned finance subsidiary of Berkshire, consist of senior unsecured notes used to fund manufactured housing loans originated or acquired and equipment held for lease of certain finance subsidiaries. In August 2018, BHFC issued $2.35 billion of 4.2% senior notes due in 2048. During 2018, BHFC repaid $4.6 billion of maturing senior notes. During January 2019, BHFC issued $1.25 billion of 4.25% senior notes due in 2049 and repaid $950 million of maturing notes. Such borrowings are fully and unconditionally guaranteed by Berkshire. In addition to BHFC’s borrowings, Berkshire guaranteed approximately $1.7 billion of other subsidiary borrowings at December 31, 2018. Generally, Berkshire’s guarantee of a subsidiary’s debt obligation is an absolute, unconditional and irrevocable guarantee for the full and prompt payment when due of all payment obligations.
Each Class A common share is entitled to one vote per share. Class B common stock possesses dividend and distribution rights equal to one-fifteen-hundredth (1/1,500) of such rights of Class A common stock. Each Class B common share possesses voting rights equivalent to one-ten-thousandth (1/10,000) of the voting rights of a Class A share. Unless otherwise required under Delaware General Corporation Law, Class A and Class B common shares vote as a single class. Each share of Class A common stock is convertible, at the option of the holder, into 1,500 shares of Class B common stock. Class B common stock is not convertible into Class A common stock. On an equivalent Class A common stock basis, there were 1,640,929 shares outstanding as of December 31, 2018 and 1,644,846 shares outstanding as of December 31, 2017.
For several years, Berkshire had a common stock repurchase program, which permitted Berkshire to repurchase its Class A and Class B shares at prices no higher than a 20% premium over the book value of the shares. On July 17, 2018, Berkshire’s Board of Directors authorized an amendment to the program, permitting Berkshire to repurchase shares any time that Warren Buffett, Berkshire’s Chairman of the Board and Chief Executive Officer, and Charlie Munger, Vice Chairman of the Board, believe that the repurchase price is below Berkshire’s intrinsic value, conservatively determined. The program continues to allow share repurchases in the open market or through privately negotiated transactions and does not specify a maximum number of shares to be repurchased. However, repurchases will not be made if they would reduce the total value of Berkshire’s consolidated cash, cash equivalents and U.S. Treasury Bills holdings below $20 billion. The repurchase program does not obligate Berkshire to repurchase any specific dollar amount or number of Class A or Class B shares and there is no expiration date to the program.