; Problem size statistics
0: Number of clauses
1: Number of variables
2: Clause/variable ratio
; 
; Variables per clause statistics
3: Mean
4: Variation coefficient
5: Min
6: Max
7: Entropy
; 
; Clauses per variable statistics
8: Mean
9: Variation coefficient
10: Min
11: Max
12: Entropy
; 
; Inter-variable statistics
13: Mean
14: Variation coefficient
15: Min
16: Max
17: Entropy
; 
; Positive variable ratio per clause statistics
18: Mean
19: Variation coefficient
20: Entropy
; 
; Positive occurrence ratio per variable statistics
21: Mean
22: Variation coefficient
23: Min
24: Max
25: Entropy
; 
; Fraction of speacial clauses
26: Fraction of binary clauses
27: Fraction of ternary clauses
28: Fraction of Horn clauses
; 
; Horn clause occurrences per variable statistics
29: Mean
30: Variation coefficient
31: Min
32: Max
33: Entropy
