Just so we're dealing with real info, I figured I'd mine the wiki. Note that this includes rubble and such - any "rare" items in the wiki.
There's roughly 39,000 "item" graphics in the game, though some of pieces of ships, etc, and wouldn't make good standalone items.
Of those, 2,345 item graphics have so far actually been used.
Used 1 time: 1,219 graphics
Used 2 times: 438 graphics
Used 3 times: 180 graphics
Used 4 times: 95 graphics
Used 5 times: 64 graphics
Used 6 times: 75 graphics
Used 7 times: 61 graphics
Used 8 times: 32 graphics
Used 9 times: 22 graphics
Used 10 times: 15 graphics
Outliers:
The 13 most used graphics kind of make sense:
13. Graphic 4161 - used 70 times. - pie
12. Graphic 4234 - used 73 times. - ring (mostly from wedding rings)
11. Graphic 5042 - used 73 times. - bow (mostly from Juka bows)
10. Graphic 5360 - used 77 times. - deed
9. Graphic 5359 - used 81 times. - deed
8. Graphic 8478 - used 86 times. - bear (valentines bears, mostly)
7. Graphic 11233 - used 112 times. - gingerbread cookie
6. Graphic 7939 - used 132 times. - robe
5. Graphic 3191 - used 151 times. - carrot
4. Graphic 2537 - used 247 times. - cake
3. Graphic 5441 - used 421 times. - sash
2. Graphic 5928 - used 520 times. - egg/lemon
1. Graphic 3628 - used 1003 times. - bottle (because there were 1000 different hues for quest bottles)
Outside of those 12, there's 131 graphics that have been used more than 10 times. Note that the plants here mostly come from pre-patch plants, rather than EM items:
So... which would you retire?