The 2016 reading also marked the highest in 10 years, the report noted.

The combined market share of South Korean goods in the US, on the other hand, advanced only 0.62 percentage point over the cited period to 3.19 percent in 2016, it added. The IIT is a private think tank run by the Korea International Trade Association, the largest trade organization here.

The report noted the FTA may have also helped the countries' overall exports grow, while those of other countries shrank.

Over the 2012-2016 period, global trade dropped by an average 2 percent per year. South Korea's overall trade also slipped by an average 3.5 percent per year over the cited period.

However, bilateral trade between South Korea and the United States grew an average 1.7 percent per year over the five-year period, according to the report.

"South Korea and the United States appear to have achieved a win-win outcome where their market shares in the other country increased at the same time based on the Korea-USFTA, despite worsening external conditions, such as a slowdown in global trade," it said.

Among the largest winners under the bilateral free trade pact were US automakers, whose combined market share in South Korea jumped an average 37.3 percent a year over the past five years to reach 18.1 percent in 2016, up 8.5 percentage points from 2011. (Yonhap)