We also have smaller serviced or leased office space in other U.K. and U.S. locations.
Amortization of deferred policy acquisition costs, general, administrative and corporate expenses
Actuarial range of net reserves. In determining the range of net reserves, we estimate recoveries due under our proportional and excess of loss reinsurance programs. For proportional reinsurance we apply the appropriate cession percentages to estimate how much of the gross reserves will be collectable. For excess of loss recoveries, individual large losses are modeled through our reinsurance program. An assessment is also made of the collectability of reinsurance recoveries taking into account market data on the financial strength of each of the reinsurance companies. The net actuarial range for reserves for losses and loss expenses assuming that net reserves move in proportion to gross would be between $3,910.2 million at the 10th percentile and $4,759.9 million at the 90th percentile. The actual net reserves established as at December 31, 2013 were $4,346.2 million (2012 - $4,280.7 million).
Net investment income. In 2013, we generated net investment income of $186.4 million, a decrease of 9.0% on the prior year (2012 - $204.9 million, 2011 - $225.6 million). This included $12.6 million in dividends from our equity investments (2012 - $6.2 million; 2011 - $6.1 million). The decrease is due to the continuing decline in our reinvestment rate over the last twelve months which reflects lower yields on investment grade fixed income securities. In 2011, lower reinvestment rates and declining book yields from fixed income securities were partially offset by $6.1 million of dividend income from global equity securities.
Interest rate swaps. As at December 31, 2013, we held a number of standard fixed for floating interest rate swaps with a total notional amount of $1.0 billion (2012 - $1.0 billion) due to mature between August 4, 2014 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. As at December 31, 2013, there was a gain in respect of the interest rate swaps of $2.6 million (2012 - $23.0 million loss; 2011 - $64.4 million loss).
Interest on long-term debt. Interest on long-term debt is the interest due on our Senior Notes, with the increase in the twelve months ended December 31, 2013 being due to our issuance of the 2023 Senior Notes in November 2013 after redeeming our $250.0 million 6.00% Senior Notes due to expire in 2014.
The decrease in reinsurance recoverables in 2013 is due to recoveries associated with losses in 2010 and 2011 in addition to an overall $35.2 million reduction in estimated recoveries for prior year events. The increase in reinsurance recoverables in 2012 was due predominantly to the recognition of recoveries associated with Superstorm Sandy and the sinking of the Costa Concordia cruise liner.
On April 11, 2012, we issued 6,400,000 Perpetual Preference Shares with a liquidation preference of $25 for an aggregate amount of $160.0 million. Each Perpetual Preference Share will receive dividends on a non-cumulative basis only when declared by our Board at an annual rate of 7.250%. The Perpetual Preference Shares have no stated maturity but are callable at our option on or after the 10th anniversary of the date of issuance. We raised net proceeds of approximately $154.5 million from this issuance.
Credit Facility. On July 30, 2010, we and certain of our direct and indirect subsidiaries (collectively the “Borrowers.”) entered into a three-year revolving credit facility with a syndicate of commercial banks under which it may, subject to the terms of the credit agreements, borrow up to $280.0 million or issue letters of credit with an aggregate value of up to $280.0 million. The facility could have been used by any of the Borrowers (as defined in the agreement) to provide funding for the operating subsidiaries of the Company, to finance the working capital needs of the Company and its subsidiaries and for general corporate purposes of the Company and its subsidiaries. The revolving credit facility further provided for the issuance of collateralized letters of credit. Initial availability under the facility was $280.0 million, and the Company had the option (subject to obtaining commitments from acceptable lenders) to increase the facility by up to $75.0 million. The expiry date of this facility was July 30, 2013.
On June 12, 2013, the Borrowers entered into an amended and restated credit agreement (the “credit agreement”) with various lenders and Barclays Bank PLC, as administrative agent, which amends and restates the credit agreement dated as of July 30, 2010 among us, certain of our subsidiaries, various lenders and Barclays Bank PLC, as administrative agent. 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, 2013, no borrowings were outstanding under the credit facility.