GMAT Critical Reasoning (CR) | Re: Because of an economic downturn in Laconia

Because of an economic downturn in Laconia, annual sales of computer companies decreased by roughly 8 percent over the last two years. Computer manufacturers that supply Laconian computer companies have noticed that the proportion of credit given to computer companies operating in Laconia and not paid off on time sharply increased over the first year of the crisis but returned to its normal level during the second year.
Which of the following, if true, best helps explain why the proportion of