"The employer contribution has shot up in the past decade to the point that it is closing in on 20 percent of payroll."

So let's compare that to the typical private sector benefits for a major employer.  Commonly, the private sector involves Social Security plus a 401(k) plan with some employer-match.  A common employer-match is 3-4% (let's say 4% to be generous).  The employer's contribution is 6.2% for SS and around 4% for 401(k) for a total of around 10%.  The employee pays 6.2% for SS and commonly around 8-10% to their 401(k), for a total of around 15%.

Per the article, PERA participants pay just 8%, while the employer nearly 20%.

Summary:
Private: Employers contribute 10%; the employee 15%
PERA: Employers contribute 20%, the employee 8%

Not much question who's getting the far more generous retirement deal.  

(And it actually may be worse that that, if "20% of payroll" means 20% of the total payroll budget. That would be at least 25% of salary.)