All empirical evidence suggests that the US Dollar got stronger against other currencies and hence people sent more. One would believe that if the beneficiary country’s currency depreciates, the same amount of money will come in, just more in local terms. Turns out, people try to send in more money to take advantage of the situation. Perhaps they want to save more. Perhaps they want to invest in some investment back home, like property/real-estate, stocks, etc.
The strong US Dollar is the only common bond in the increase.