Natural gas vs coal stocks

• coal stocks: KOL, BTU, WLT, CNX, ACI, ANR, JRCC, YZC, ARLP, AHGP, NRP, PVR, PVG, PVA, OXF, CLD, WLB, RNO
• finviz (by vol) http://finviz.com/screener.ashx?v=211&ta=0&o=-averagevolume&t=KOL,%20BTU,%20WLT,%20CNX,%20ACI,%20ANR,%20JRCC,%20YZC,%20ARLP,%20AHGP,%20NRP,%20PVR,%20PVG,%20PVA,%20OXF,%20CLD,%20WLB,%20RNO