South Korean exports, a data set often held up as a bellwether for the health of the global economy, fell off a cliff in January, pointing to a troubling slowdown in global trade.Exports from the east Asian nation dropped 14.6% in the first 20 days of 2019 versus the same period last year, according to data released Monday morning. That compared to an increase of 1% over the same period in December.”Growth at the margins is getting very ugly — 20-day exports fell at an annualized rate of 38.6% in the three months to January, seasonally adjusted, much sharper than the 19.2% fall in the three months to December,” Beamish wrote.