For investors, the next best thing to a fortune teller is the Dow Jones Transportation Index. The index -- often referred to as "Dow Transports" for short -- is made up of 20 top railroad, airline, trucking and delivery services stocks. Think: Delta (DAL), FedEx (FDX) and Union Pacific (UNP). When it goes up, the rest of the stock market often follows. And when it goes down, well, you get the idea. Right now, the Dow Transports (DJT)is sinking. It peaked on December 29 and has been sliding pretty much since then. It's now down 9% in 2015. "There's anxiety...