NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (in thousands, except for share and per share data)
NOTE 12 — Debt
Long-term debt was comprised of the following:
On February 12, 2019, we entered into an amended and restated five-year Credit Agreement with a group of banks (the "Credit Agreement") to extend the term of the facility. The Credit Agreement provides for a revolving credit facility of $300,000, which may be increased by $150,000 at the request of the Company, subject to the administrative agent's approval. This new unsecured credit facility replaces the prior $300,000 unsecured credit facility, which would have expired August 10, 2020. Borrowings of $50,000 under the prior credit agreement were refinanced into the Credit Agreement. The prior agreement was terminated as of February 12, 2019.
The Revolving Credit Facility includes a swing line sublimit of $15,000 and a letter of credit sublimit of $10,000. Borrowings under the Revolving Credit Facility bear interest at the base rate defined in the Credit Agreement. We also pay a quarterly commitment fee on the unused portion of the Revolving Credit Facility. The commitment fee ranges from 0.20% to 0.30% based on our total leverage ratio.
The Revolving Credit Facility requires, among other things, that we comply with a maximum total leverage ratio and a minimum fixed charge coverage ratio. Failure to comply with these covenants could reduce the borrowing availability under the Revolving Credit Facility. We were in compliance with all debt covenants at December 31, 2019. The Revolving Credit Facility requires that we deliver quarterly financial statements, annual financial statements, auditor certifications, and compliance certificates within a specified number of days after the end of a quarter and year. Additionally, the Revolving Credit Facility contains restrictions limiting our ability to: dispose of assets; incur certain additional debt; repay other debt or amend subordinated debt instruments; create liens on assets; make investments, loans or advances; make acquisitions or engage in mergers or consolidations; engage in certain transactions with our subsidiaries and affiliates; and make stock repurchases and dividend payments. Interest rates on the Revolving Credit Facility fluctuate based upon the LIBOR and the Company’s quarterly total leverage ratio.
We have debt issuance costs related to our long-term debt that are being amortized using the straight-line method over the life of the debt. Amortization expense for the twelve months ended December 31, 2019 was approximately $163 and $185 in 2018 and 2017. These costs are included in interest expense in our Consolidated Statement of Earnings.
We use interest rate swaps to convert the revolving credit facility's variable rate of interest into a fixed rate on a portion of the debt as described more fully in Note 13 "Derivatives." These swaps are treated as cash flow hedges and consequently, the changes in fair value were recorded in other comprehensive earnings.
Table:
 | As of December 31 | 
 | 2019 | 2018
Total credit facility | $300,000 | $300,000
Balance outstanding | $99,700 | $50,000
Standby letters of credit | $1,800 | $1,940
Amount available | $198,500 | $248,060
Weighted-average interest rate | 3.25% | 3.10%
Commitment fee percentage per annum | 0.23% | 0.20%


Question: How did the company convert the revolving credit facility's variable rate of interest into a fixed rate on a portion of the debt?
Answer: interest rate swaps