Hi Doug. I just sent Manfred (philastore) a SOR message about your post. He is my go-to guy here in the States on Germany and should be able to supply the correct answer for your item.
The number of holes refers to the whole perforation holes, either top or bottom, and sides on the stamps. This helps to ID the different printings with the same perf gauge reading.
No guarantee, my take is 2011 Scott #79, and 1971 Minkus #77.
Minkus lists perf 14 1/2 and perf 14 1/2 x 14 with 26x17 holes issued March 20 1902,the 26x17 holes matches the number of perf holes on your stamp 26 horizontal and 17 vertical.
