A generation ago, one popular song implored workers to tell their bosses to “Take This Job and Shove It.” Judging from how many Americans are choosing retirement, millions are taking that advice.Economists long expected the share of retirees in the population to soar as baby boomers aged. Covid-19 then caused the number to spike well beyond expectations, a surge dubbed the “Great Retirement Boom.” But just as they seemed to be coming back down, the numbers surged again in recent months, reaching...