No stat on iS seems to match any other stat.
One reason is that although sub sales record in almost real time on the year-to-date counter, they don't always count as sales in the calendar month, because subs can carry forward, and the calculation is done when the carry-forward ends. That often/usually means that the value to us of a sub is higher than it was when we got flat rates.
Also if you're exclusive, 'plussed' file sales count as 2 on the ytd counter. That doesn't apply to indies.
Other than that ... they have said that the ytd counter 'pulls stats from a different source', so
