The
relationship is very approximate,
but it is clearly significant and
follows the sort of pattern we
would expect. There are three reasons
why rich countries with a
high GNP might be expected to
have a higher level of imports
than a poor country with low
GNP. First, a larger economy has
greater needs in terms of the raw
materials and manufactured
goods which are shipped by sea.
Some of these will not be available
locally. Second, matureeconomies which started out with plentiful local resources will eventually use them up,
leading to the need for imports. For example, the USA started out with abundant oil
reserves but now imports more than half its requirements. Third, a country with high
GNP can afford to purchase imports and has more to export in return.