math
posted by Re re on .
The price of a certain commodity is a function of supply and demand. The table below shows the price of commodity per barrel between 1995 and 2000. Find the average anual rate of change between 1998 and 2000.
Year Price/barrel
1995 $19
1996 $24
1997 $17
1998 $11
1999 $24
2000 $35
Please explain how to get the answer

9899
24  11 = 13
13/11 = 1.18 = 118%
9900
35  24 = 11
11/24 = 0.458 = 45.8%
(118 + 45.8)/2 = ?