=+a. To examine the degree of change, calculate the year-to-year proportional change by subtracting the 2017 ratio from the 2018 ratio and then dividing the difference by the year 2017 ratio. Multiply the result by 100 to get percentage change in the given ratio. Preserve the positive or negative sign to indicate the direction of change. Calculate the proportional change for all the ratios provided in the table.