Ah! My Goddess manga has run from september 1988 to june 2014, and that is 25 years, 9 months.
Of the manga series that have already ended by this posting (before september 2016), what is the longest-running one?
Is it Ah! My Goddess? Or is there an even longer one?
I'm more interested in the time between the first and the last chapter, but if you can in addition to make a point for the one with more chapters, that is also acceptable