A plunge in exports and the worst growth rates for a decade have fuelled concerns about the outlook for Singapore's economy, with analysts saying the figures offer a warning that Asia is heading for a slowdown as China-United States (US) tensions bite.While it may be one of the smallest countries in the world, the export hub is highly sensitive to external shocks and has long been viewed as a barometer of the global demand for goods and services.The affluent city-state is highly dependen