The Sensex at the Bombay Stock Exchange dropped 204 points, or 1.1 percent, to a five-week low of 18,110, on Tuesday, on concerns about domestic economic growth, and in tandem with falling global bourses. The Nifty at the National Stock Exchange fell 60 points, or 1.1 percent, to 5,457.Stock markets in Japan, China, Hong Kong, Singapore, and South Korea dropped between 0.9 percent and 2.4 percent, on fresh indications that US manufacturing growth is slowing.