Can anyone help me to write the regular expression to match a number if the next line begins with a word?

I want to match 2,021 which is present at the second last word on the third line with the respect of Demand which the first word of the fourth line.

Input:

Days of

Service

Electric 0156887974 02/24/23 60,170 01/24/23 58,149 1 2,021 31

Demand 0156887974 02/24/23 9.62 01/24/23 10.39 1 9.62 31
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