One of the chief difficulties in statistics is separating out two effects which (as it happens) seem to be linked. As time goes on it may become clear there was no such link. A certain amount of common sense is needed here.
1) If the demand for a commodity falls (due to installing condensing boilers) then it's price is likely to fall. 2) Energy prices are subject to global market forces. 3) As "Dubya" would say there is a trouble in "Iraqistan".