16. Retirement Plans

We maintain qualified 401(k) plans which cover substantially all employees meeting certain eligibility requirements. Participants may contribute a portion of their compensation to the plans, up to the maximum amount permitted under Section 401(k) of the Internal Revenue Code. Under these plans, we contribute various percentages of employees’ salaries to the plans. Total expenses included in operating expenses in the accompanying consolidated statement of operations related to the plans were $4.7 million, $4.1 million and $3.8 million for the years ended December 31, 2024, 2023, and 2022, respectively.