New Delhi, Oct. 22 -- Annual growth in eight key infrastructure sectors, as measured by the combined Index of Eight Core Industries (ICI), fell to the slowest in 3 months in September due to a weakening output in the energy sector, after reaching a 15-month high in August, according to data released by the Ministry of Commerce and Industry on Tuesday. The September reading came in at 3%, down from 6.5% in August. On a month-on-month basis the index contracted by 3.8%. The eight sectors counted in the index are coal, crude oil, natural gas, refinery products, fertilisers, steel, cement, and electricity. They comprise 40.3% of the weight of items included in the Index of Industrial Production (IIP). The slowdown in the core sector reading is ...