The Following Table Presents Data on Imports and Exports as a Percentage

The following table presents data on imports and exports as a percentage of gross domestic product GDP) for select countries in 2015, based on data from the World Bank. $$\begin{array} { l l l } \hline \text { Country } & \begin{array} { l } \text { Exports as a } \\\text { Percentage of GDP }\end{array} & \begin{array} { l } \text { Imports as a } \\\text { Percentage of GDP }\end{array} \\\hline \text { Australia } & 19.8 & 21.2 \\\text { Belgium } & 84.4 & 82.7 \\\text { Chile } & 30.1 & 30.3 \\\text { China } & 22.4 & 18.8 \\\text { South Korea } & 45.9 & 38.9 \\\text { United States } & 12.6 & 15.5 \\\hline\end{array}$$ Why might some of these countries tend to have much larger values for imports and exports as a percentage of GDP in comparison to other countries?