South Korea's dependence on overseas trade exceeded 90 percent of the national income last year for the first time, leaving the nation's economy more vulnerable to fluctuations in global market conditions.

According to data released by Statistics Korea, formerly the National Statistical Office, and the Finance Ministry, the nation's trade dependence ratio or the proportion of trade to gross national income soared to a record 92.3 percent last year, up from 69.4 percent a year earlier.

The ratio had stayed at around 50-60 percent over the past decade but surged over 90 percent for the first time last year when the global economy plunged into chaos in the wake of financial turmoil, according to Yonhap News Agency.

Higher trade dependence means that the economy is more vulnerable to ups and downs in external market conditions. Last year's ratio for South Korea was the 11th highest among 93 countries surveyed by the statistics office and the ministry.

The comparable ratio for Japan stood at 31.6 percent, while those for India, Australia and Britain were 37.7 percent, 39.1 percent and 41.2 percent, respectively, suggesting that those countries have well-nurtured domestic markets that can better shield them from a possible plunge in demand from overseas markets during a global economic downturn.

Policymakers are mapping out plans to reduce the country's heavy trade dependence and expand its domestic markets as part of efforts to fuel economic growth.

In a related move, the government has been pushing to nurture its service sector, deemed to be critical in creating new jobs and helping reduce the country's exposure to external market fluctuations.