ZURICH, Dec 18 (Reuters) - Switzerland’s third-quarter current account surplus shrank to 9 billion Swiss francs ($10.17 billion), 3 billion less than a year earlier, the Swiss National Bank said on Friday. The figure marked a downturn from the 9.88 billion surplus posted in the second quarter. “This decline was particularly due to the lower receipts surplus in trade in goods and services. In the case of the goods trade, the decline was attributable to gold trading,” the SNB said in a statement.