Sentence:  The maximum <WSD>amount</WSD> of payments which may be made pursuant to this Act on account of sales of newly mined ores or concentrates produced therefrom made during the calendar year 1962 shall not exceed $ 4500000 ; the maximum amount of such payments which may be made on account of such sales made during the calendar year 1963 shall not exceed $ 4500000 ; the maximum amount of such payments which may be made on account of such sales made during the calendar year 1964 shall not exceed $ 4000000 ; and the maximum amount of such payments which may be made on account of such sales made during the calendar year 1965 shall not exceed $ 3500000 . 
Meaning of the word marked with <WSD> tags:  a quantity obtained by the addition of a group of numbers