From: Computational RNA secondary structure design: empirical complexity and improved methods
Hairpins
Stems
2-Branch loops
Multiloops
Bulges
Size
[4,8]
[3,12]
[4, 11]
[6,17]
[1,3]
Number
-
[1,8]
[0,5]
[0,0.17]*
Branches
[3,4]