Commodity200520062007200820092010
Heterocyclic comps. cont. an unfused pyrazole ring (whether or not hydrogen ...$827 $2,451  $2,564
Heterocyclic comps. cont. an unfused imidazole ring (whether or not hydroge ...$2,510  $821$1,587 
Pyridine & its salts$77     
Heterocyclic comps. cont. an unfused pyridine ring (whether or not hydrogen ... $1,656$33,150$9,501$37,110$4,711
Heterocyclic comps. cont. a pyrimidine ring (whether or not hydrogenated)/p ...$5,725$11,788$18,798$629  
Melamine$39 $961$664 $25,893
Heterocyclic comps. cont. an unfused triazine ring (whether or not hydrogen ...$1,912$812$3,702$658 $34,299
6-Hexanelactam (epsilon-caprolactam) $932$24   
Total$11,090$15,188$59,086$12,273$38,697$67,467