Variation Comparison between variation of bills from 2006 to 2014 and inflation (annual average increase, CAGR) Considering a longer timescale (2006-2014), it can be noticed that gas, electricity, water service and waste management bills recorded a lower increase in the Emilia Romagna area served by Hera compared to the increase at national level (average yearly increase of 3.4% compared 4.6% relating to Italy).