CNBC's Jim Cramer on Monday told investors why he believes that a government shutdown won't have a major effect on the market, looking back at how stocks have reacted to shutdowns in the past. He said his primary concern is that the shutdown will delay the release of key economic data that informs the Federal Reserve's decision on interest rates."When it comes to government shutdowns, my message is simple: keep calm and carry on, because the stock market tends to do just fine in these situations," Cramer sa ...