Data from the period of 1980e2007 are applied to train the
network. Data for the years of 2008e2012 are used exclusively in
the test procedure to evaluate the performance of the model. Data
are gathered from reliable sources. For example, total energy
consumed in the industrial sector is published by the EIA (Energy
Information Administration) [38]. Also, prices of energy carriers
(electricity, natural gas, diesel fuel and propane) are taken from
monthly reports of the EIA [54]. GDP data are obtained from the
World Bank [55]. The trends of mentioned independent parameters
for the period of 1980e2012 are shown in