14. Defined Contribution Plan

We administer a 401(k) savings plan, a defined contribution plan covering substantially all of our employees. Employees in the plan may contribute up to the maximum annual IRS limit before taxes via payroll deduction. Under the plan, we provide a dollar for dollar match for the first 4% of the employee’s contributions and a $0.50 per dollar match for the next 2% of employee contributions. We contributed less than $1 million under the plan for the years ended December 31, 2017, 2016, and 2015, respectively.