NICS Checks - A Meaningful Record?

People like to proclaim "New Record" every time NICS check numbers exceed the previous year by some small amount, without taking into consideration that with the population increasing, the numbers can be expected to go up regularly.

Last month however, the numbers took a significant jump, putting May ahead of every May so far by a generous margin and ignoring the traditional trend of declining going in to the Summer:

Not sure what might be causing this, maybe more disposable income among the population (possible), maybe increasing expectation of violent revolt (unlikely). or something else. Theories, anyone?