As far as I know, the only way is to find it in your store backend - like search for it on your products page - then switch to the digital stats tab and it will show you the stats for digital sales. It really only works to do it one product at a time though, because even if you're in the digital tab, the sorting (and I assume the other filters too) still uses the printed stats to sort by... so yeah, it's clumsy to say the least, but you can at least get the info one product at a time. I'd LOVE to know if anybody has a better method!
