Amortization of deferred policy acquisition costs increased in 2014 compared to 2013, and in 2013 compared to 2012, in line with premium growth in our U.S. insurance operations and due mainly to adjustments in profit-related commission accruals. General, administrative and corporate expenses have increased to $445.7 million in 2014 from $368.1 million in 2013 and $345.1 million in 2012. The increase in 2014 is due to an increase in staff costs, performance-related accruals, costs associated with the continued build out of our U.S. insurance and expenses attributable to defending the unsolicited approach for an inadequate offer by Endurance at a cost of $28.5 million.
Selection of reported gross reserves. Management, through its Reserve Committees, then reviews the range of actuarial estimates, which to date it has not adjusted, and any other evidence before selecting its best estimate of reserves for each class of business. Management may select its best estimate outside the range provided by the actuaries, but to date gross reserves have been within the range of actuarial estimates. This provides the basis for the recommendation made by management to the Audit Committee and the Board regarding the reserve amounts to be recorded in the Company’s financial statements.
Our consolidated financial statements are prepared in accordance with U.S. GAAP. The discussions that follow include tables and discussions relating to our consolidated income statement and our segmental operating results for the twelve months ended December 31, 2014, 2013 and 2012.
Gross written premiums. The following table analyzes the overall change in gross written premiums in the twelve months ended December 31, 2014, 2013 and 2012.
Total gross written premiums increased by 9.7% in 2014 when compared to 2013 predominantly due to increases from our insurance lines, with growth from all our U.S. teams, our international property and casualty business lines and from international financial and professional lines. We have experienced more modest growth from our reinsurance lines due to challenging market conditions. Gross written premiums also included reinstatement premiums and other premiums receivable directly related to losses arising from all catastrophic events of $Nil (2013 - $7.0 million; 2012 - $23.3 million).
Interest rate swaps. As at December 31, 2014, we held a number of standard fixed for floating interest rate swaps with a total notional amount of $951.3 million (2013 - $1.0 billion) due to mature between November 26, 2015 and November 9, 2020. The interest rate swaps are used in the ordinary course of our investment activities to partially mitigate the negative impact of rises in interest rates on the market value of our fixed income portfolio. In 2014, we decided to let our interest rate swap program roll off and not renew maturing positions. We took this decision after an extensive reassessment of the costs of maintaining an interest rate swap program in a steep yield curve environment. As at December 31, 2014, there was a loss in respect of the interest rate swaps of $7.2 million (2013 - $2.6 million gain; 2012 - $23.0 million loss).
At December 31, 2014 and December 31, 2013, total cash and investments, including accrued interest receivable, were $8.6 billion and $8.3 billion, respectively. We follow an investment strategy designed to emphasize the preservation of capital and provide sufficient liquidity for the prompt payment of claims. As of December 31, 2014, our investments consisted of a diversified portfolio of fixed income securities, global equities, catastrophe bonds and money market funds. In keeping with our strategy of improving long term investment returns and in light of the ongoing low interest rate environment, we adjusted our asset allocation by increasing our equity exposure by $240.0 million from 5.6% to 8.5% of our investment portfolio. We also sold our $25.1 million BB High Yield Bonds portfolio in May 2014 since we thought the market was expensive and could not find securities that met our portfolio criteria. We continue to maintain a 1.0% position in BB Bank Loans and a 2.5% position in BBB Emerging Market Debt. As at December 31, 2014, approximately 12.5% of our Managed Portfolio was invested in equities, BB Bank Loans and BBB Emerging Market Debt. We continue to evaluate investment opportunities that will help us generate increased returns, while remaining within our risk tolerances.
Management monitors the ratio of debt to total capital, with total capital being defined as shareholders’ equity plus outstanding debt. At December 31, 2014, this ratio was 17.0% (December 31, 2013 - 15.4%).
Operating Subsidiaries. As of December 31, 2014, the Operating Subsidiaries held $1,296.2 million (December 31, 2013 - $1,150.2 million) in cash and short-term investments that are readily realizable securities. Management monitors the value, currency and duration of cash and investments held by its Operating Subsidiaries to ensure that they are able to meet their insurance and other liabilities as they become due and was satisfied that there was a comfortable margin of liquidity as at December 31, 2014 and for the foreseeable future.
Holdings, the Borrowers, various lenders and Barclays. The credit facility is used to finance our working capital needs and those of our subsidiaries for letters of credit in connection with our insurance and reinsurance businesses and for other general corporate purposes. Initial availability under the credit facility is $200.0 million and we have the option (subject to obtaining commitments from acceptable lenders) to increase the facility by up to $100.0 million. The facility will expire on June 12, 2017. As of December 31, 2014, no borrowings were outstanding under the credit facility.
Inflation may have a material effect on our consolidated results of operations by its effect on interest rates and on the cost of settling claims. The potential exists, after a catastrophe or other large property loss, for the development of inflationary