Sentence:  Beginning in 1960 , the matching requirements for the base allotment are being adjusted ( upward or downward , as required ) 25 % <WSD>a</WSD> year , so that by 1963 the entire support allotment will be matched on the basis of a 40 % pivot State share , with maximum and minimum State shares of 50 % and 30 % , respectively . 
Meaning of the word marked with <WSD> tags:  by the year; every year (usually with reference to a sum of money paid or received)