The Company sponsors the SkyWest, Inc. Employees’ Retirement Plan (the “SkyWest Plan”). Employees who have completed 90 days of service and are at least 18 years of age are eligible for participation in the SkyWest Plan. Employees may elect to make contributions to the SkyWest Plan. Generally, the Company matches 100% of such contributions up to levels ranging from 2% to 12% of compensation, based on position and years of service. Additionally, a discretionary contribution may be made by the Company. The Company’s combined contributions to the SkyWest Plan were $40.7 million, $35.6 million and $26.1 million for the years ended December 31, 2019, 2018 and 2017, respectively.

In May 2009, the Company’s Board of Directors approved the SkyWest, Inc. 2009 Employee Stock Purchase Plan (the “2009 Stock Purchase Plan”). All employees who have completed 90 days of employment with the Company or one of its subsidiaries are eligible to participate in the 2009 Stock Purchase Plan, except employees who own five percent or more of the Company’s common stock. The 2009 Stock Purchase Plan enables employees to purchase shares of the Company’s common stock at a five percent discount, through payroll deductions. Employees can contribute up to 15% of their base pay, not to exceed $25,000 each calendar year, for the purchase of shares. Shares are purchased semi-annually at a five percent discount based on the end of the period price. Employees can terminate their participation in the 2009 Stock Purchase Plan at any time upon written notice.

The following table summarizes purchases made under the 2009 Employee Stock Purchase Plans during the years ended December 31, 2019, 2018 and 2017:

The 2009 Stock Purchase Plan is a non-compensatory plan under the accounting guidance. Therefore, no compensation expense was recorded for the years ended December 31, 2019, 2018 and 2017.