The table represents an exponential function.

A 2-column table has 4 rows. The first column is labeled x with entries 1, 2, 3, 4. The second column is labeled y with entries three-halves, nine-eigths, StartFraction 27 Over 32 EndFraction, StartFraction 81 Over 128 EndFraction.

What is the multiplicative rate of change of the function?