A special purpose index is to be designed to monitor the overall economy of Penang. For key series were selected which are retail sales, total bank deposits, industrial production and non-agricultural employment. After considerable deliberation, it was decided to weight retail sales 20%, total bank deposits 10%, industrial production 40% and non-agricultural employment 30%. The data for 1996 and 2018 are: Year Retail Sales (RM million) Bank Deposits (RM billion) Industrial Production (1990=100) Employment 1998 1,159 87 110.6 1,214,000 2018 1,971 91 114.7 1,501,000 Construct a special purpose index for 2018 using 1996 as the base period and interpret.