Site of an Eastman Chemical plant in Kingsport, Tennessee. Eastman is one of a few companies whose insiders have recently purchased their own stock. (Photo by Earl Neikirk/For The Washington Post via Getty Images)The Washington Post via Getty ImagesThis column frequently tracks insider buys by companies’ chief executives. Lately, they are scarce.Executives normally sell more shares than they buy because their cup is periodically refilled via stock-option grants. Over the past 21 years, according to Gurufocu ...