The nation’s largest senior advocacy group has issued its annual rating for businesses it designates as among the 15 “best” for older workers, and two Iowa businesses made the list: Principal Financial in Des Moines and The Stanley Group of Muscatine.Laurie McCann of A-A-R-P says it’s similar to “Working Mother” magazine’s rating of the best places for moms to work. McCann says the association hopes to get the same result “Working Mother” has gotten — companies compete to make the list.Businesses get extra points if the company’s former workers or even folks who’ve retired are recruited for job openings. McCann says a company’s corporate culture and career development paths are evaluated, too, to ensure that older workers are passed over for promotions. McCann says A-A-R-P hopes the project helps debunk stereotypes about older workers.McCann says research shows the productivity of older workers doesn’t decline with age, and there’s no truth to the notion that older workers have more serious health problems than their younger counterparts. She says there is one huge difference between older and younger workers: older employees tend to be more loyal to their employer.