I've done a couple things here. First, I've knocked out the totals for years that are multiples of ten, as editions that have been dated "ca. 1670" and the like would give them undue weight. I've added a 2-year moving average trend line to compensate.
The results seem quite clear. After a burst of printing activity just before 1620, the number of titles declines precipitously. There is an interesting spike in 1630-31 that deserves more scrutiny, and then the number of titles printed annually declines even farther. The recovery beginning in 1640 does not reach pre-war levels until 1660.
Beyond looking at titles, we can also get an impression of how much paper was being consumed by the publishing industry by estimating the number of sheets each book required. Instead of counting titles, we divide the total number of leaves in a book by its format, then add the result for all books published in a given year. We have to ignore differing paper sizes and print runs, so the results have to be treated with caution, however. With that in mind, the result looks like this:
I've knocked out the round decades again. Because the data is noisier, I've added a 5-year moving average. In this view, the decline in German publishing due to the Thirty Years' War is deeper - a decline of nearly 70% compared to a decline of titles by 50% - and longer lasting. The publishing industry's consumption of paper doesn't appear to entirely regain its prewar level even by the end of the century. We have to keep in mind that there might be other explanations. Perhaps publishers were choosing larger paper sizes and thus needing fewer total sheets, or perhaps they were printing larger print runs than earlier.