Write a formula for a linear function that models the situation. Choose both an appropriate name and an appropriate variable for the function. State what the input variable represents and the domain of the function. Assume that the domain is an interval of the real numbers.

In 1992 the number of injury cases recorded in private industry per 100 full-time work- ers was 8.3, and it decreased, on average, by 0.23 injury every year until 2015.