Explanation:

The level of the Index of Industrial Production (IIP) is an abstract number, the magnitude of which represents the status of production in the industrial sector for a given period of time as compared to a reference period of time. The base year was at one time fixed at 1993–94 so that year was assigned an index level of 100. The current base year is 2011-2012.

The Eight Core Industries comprise nearly 40.27% of the weight of items included in the Index of Industrial Production (IIP). These are Refinery products, Electricity, Steel, Coal, Crude oil, Natural gas, Cement and Fertilisers.(Arranged in descending order of their share).