I do not know percentages because I do not measure them but my baby thayeri is requiring significantly higher humidity levels then my baby corns.
However my yearling thayeri is only requiring about the same as my baby corns.
If you use a damp hide or if you spray the enclosure twice a week you should be fine for a baby.
Just keep an eye on their sheds and if they are incomplete then up the humidity. Safest option though is a moist hide in addition to their regular hide.
And here is the link Michelle sent me for the Thayeri caresheet written by John Cherry on this site
http://www.kingsnake.com/king/mexicana/thayeri.html
Sean
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1.1 BRB
1.1 Triple Het TPRS's
1.1 Amel Bloodred Corns
0.1 Abbott Okeetee Corn
0.1 Blizzard Bloodred Corn
1.1 Thayeri Kingsnakes
0.1 Reeve's Turtle
0.2 Amstaff's
1.0 Pudytat