Monthly usage data for pallets used in a distribution center are as follows:

Month$1234$January$1,4841,4821,7921,902$February$1,3941,4001,5861,722$March$1,5521,5481,7701,876$April$1,7961,8642,1102,218$May$2,0602,1982,4082,548$June$2,2142,4462,6522,844$July$2,3302,5802,6062,972$August$2,4322,6982,8723,110$September$2,4162,6822,9463,208$October$2,2622,5922,9063,200$November$1,9422,1322,3402,806$December$1,5661,8022,0462,418$

Calculate the monthly usage index for each month.

Use simple linear regression to forecast total usage of pallets for year $5.$