Debt obligations consist of the following (in thousands):


	December 31,
	2023		2022
Revolving credit facility	$	—	$	215,000
Notes to former owners		44,070		41,040
Other debt		142		205
Total debt		44,212		256,245
Less—current portion		(4,867)		(9,000)
Total long-term portion of debt	$	39,345	$	247,245


	Year Ended December 31,
	2023		2022		2021
Interest expense on notes to former owners	$	1,365	$	1,139	$	1,052
Interest expense on borrowings and unused commitment fees		7,507		10,955		3,371
Interest expense (income) on interest rate swaps		—		(332)		499
Interest expense on finance leases		—		4		57
Letter of credit fees		724		800		679
Amortization of debt financing costs		685		786		538
Total	$	10,281	$	13,352	$	6,196


	Net Leverage Ratio
	Less than 1.00		1.00 to less than 1.75		1.75 to less than 2.50		2.50 to less than 3.00		3.00 or greater
Additional Per Annum Interest Margin Added Under:
Base Rate Loan Option	0.00	%	0.25	%	0.50	%	0.75	%	1.00	%
SOFR Loan Option	1.00	%	1.25	%	1.50	%	1.75	%	2.00	%
Letter of credit fees	1.00	%	1.25	%	1.50	%	1.75	%	2.00	%
Commitment fees on any portion of the Revolving Loan capacity not in use for borrowings or letters of credit at any given time	0.15	%	0.175	%	0.20	%	0.225	%	0.25	%

At December 31, 2023, future principal payments of notes to former owners by maturity year are as follows (dollars in thousands):