Based on a comparison of 167 countries in 2016, Hong Kong ranked the highest in merchandise trade as a share of GDP with 332% followed by Singapore and Vietnam. On the other end of the scale was Sudan with 11.5%, Cuba with 17.3% and Nigeria with 17.7%.
Average merchandise trade as a share of GDP reached 50.0% in 2016 in the World according to the National Statistical Office. This is 11.4 % more than in the previous year and 4.29 % more than 10 years ago.
Historically, average merchandise trade as a share of GDP reached an all time high of 51.6% in 2008 and an all time low of 16.8% in 1962. The average annual growth amounted to 1.89 % since 1960.
Data for more countries are available at Merchandise Trade (As % of GDP) indicator page.