Morning/Afternoon!
I had an old account I never use with 20 seals and used all of them to test it out.

4 Total Pulls- Guy
9 Total Pulls- Kimimaru
13 Pulls- Sasori (Rare 60 Seals)
17 Pulls- Deidara (Rare 60 Seals)
20 Pulls- Kisame (Rare 60 Seals)

180 Seals worth of rare ninja for 20 Seals

So 9 times more ninja for your Seals.(Depended on Pulls of cause)