You are looking at the previous report. The data out for April 2015 shows:
457,305 Thousand Megawatthours = coal
92,516 Thousand Megawatthours = natural gas
http://eia.gov/electricity/monthly/epm_table_grapher.cfm?t=epmt_1_01
Graphed at: http://eia.gov/electricity/data/browser/#/topic/0?agg=2,0,1&fuel=vvg&geo=g&sec=g&linechart=ELEC.GEN.ALL-US-99.M~ELEC.GEN.COW-US-99.M~ELEC.GEN.NG-US-99.M~ELEC.GEN.NUC-US-99.M~ELEC.GEN.HYC-US-99.M&columnchart=ELEC.GEN.ALL-US-99.M~ELEC.GEN.COW-US-99.M~ELEC.GEN.NG-US-99.M~ELEC.GEN.NUC-US-99.M~ELEC.GEN.HYC-US-99.M&map=ELEC.GEN.ALL-US-99.M&freq=M&start=200101&end=201504&ctype=linechart<ype=pin&rtype=s&maptype=0&rse=0&pin=
you convinced me ;-)