Consider the function graphed below

For this case we have two study intervals.
 For x <1:
 In this interval we have the following equation:
 f (x) = x ^ 2
 For x> 1:
 In this interval we have the following equation:
 f (x) = (1/3) x + 2/3
 
 The graph represents the following function:
 f (x) = x ^ 2 (x <1)
 f (x) = (1/3) x + 2/3 (x> 1)

It is 6% because if you subtract 69-58=6 so 6% is the answer to your question.