The collector shall collect on delinquent assessments for the use of the district the following penalties:

(a) When assessments are not payable in installments, 5 per cent.

(b) When assessments are payable in installments:

(1) On the first installment, 10 per cent.

(2) On the second installment, 5 per cent.

(Added by Stats. 1943, Ch. 372.)