how would u calculate monthly return for each month using adjusted closed prices?

High null Close null 59.84 53.790001 54.540001 48.622025 Date Adj Close null Open Low 4/1/13 null null 54.82 49.057472 56.77 50.802498 59.98 53.675064 60.52 64.23999857.487259 10/1/13 64.51000266.58999662.75999864.04000157.499905 5/1/13 54.599998 6/1/13 54.709999 7/1/13 55.080002 8/1/13 57.330002 55.5 49.150002 59.52 53.349998 60.32 57.299999 60.6665.150002 11/1/13 64.309998 67.75 63.119999 67.01999760.175552 69.7565.59999869.239998 62.168835 12/1/13 66.93 1/1/14 69.190002 70.040001 61.57 61.6899955.560886