These are some statistics to keep in mind regarding ballpark talent replacement costs:
$7,000 salaried Worker    $10,000 Mid-level Employee    $40,000 Senior Executive
Did you know that Business.com says 45% of employees are dissatisfied in their job, and of this group, the under-25 employees are the most unhappy? 
In Oregon, you can enter a free employee engagement survey by vying for the Oregon Business Magazine's 100 Best Companies to Work For in Oregon award.  Your employees fill out confidential survey data, and you, the employer, can obtain that data from Oregon Business and see how your employees feel about your workplace.  Things like Compensation, Benefits, Work Conditions, Ethics, Management, etc. 
My caveat is if you find out what's bugging your employees, then you better take steps to change things once you get the data, or morale and trust will erode significantly from their dashed hopes.