I have no idea about the stats
but are the 90 really that underpresented this tour
given that U2 only released 3 albums in that decade (compared to 6 in the 80s and I do expect more 00s material since it is more recent)
whether you count Passengers as a U2 album or not, it doesn't really have more than 3 songs they could transform to a live show
One and Ultraviolet get played every show
Until the end, Stay and now Your Blue Room seem to appear regularly
do the 80s really get a lot more songs in there?
(taken into consideration there is twice as much material to chose from)
Let's consider all the songs in 'regular circulation':
1. Breathe
2. NLOTH
3. Boots
4. Magnificent
5. Beautiful Day
6. Mysterious Ways
7. Elevation
8. Still Haven't Found
9. Your Blue Room
10. New Year's Day
11. Unknown Caller
12. UTEOTW
13. Stuck
14. Stay
15. The Unforgettable Fire
16. City
17. Vertigo
18. Crazy Tonight
19. Sunday Bloody Sunday
20. MLK
21. Walk On
22. One
23. Streets
24. Ultraviolet
25. With or Without You
26. Moment of Surrender
We can break this down into five chunks:
Boy-October-War Era: Two songs (SBS, NYD)
TUF-TJT-R&H: Five (SHF, TUF, MLK, Streets, WOWY)
Achtung-Zooropa-OS1-Pop: Six (MW, YBR, UTEOTW, Stay, One, UV)
ATYCLB-Bomb: Six (BD, Elevation, Stuck, City, Vertigo, Walk On)
NLOTH: Seven (Breathe, NLOTH, Boots, Magnificent, Unknown Caller, Crazy Tonight, MOS)
In that context, six songs for the 90s doesn't seem that bad, although only two of those are true fixtures, as opposed to one from the early 80s, all five from the late 80s, five from ATYCLB-Bomb, and all seven from NLOTH.