If so, then what are the A and B terms in an (A/B) expression like 10,000 cases out of 100,000 unit sales? Numerator, denominator? Does any country's FDA AERS

If so, then what are the A and B terms in an (A/B) expression like 10,000 cases out of 100,000 unit sales? Numerator, denominator? Does any country's FDA AERS collect unit sales data?