I have daily stock market data and would like to calculate the return for each observation relative to the peak in the last 6 months. I've tried fishing around for a solution, but I am stuck trying to code this in.

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str10 date float value
"2009-02-02" 825.44
"2009-02-03" 838.51
"2009-02-04" 832.23
"2009-02-05" 845.85
"2009-02-06"  868.6
"2009-02-09" 869.89
"2009-02-10" 827.16
"2009-02-11" 833.74
"2009-02-12" 835.19
"2009-02-13" 826.84
"2009-02-16"      .
"2009-02-17" 789.17
"2009-02-18" 788.42
"2009-02-19" 778.94
"2009-02-20" 770.05
"2009-02-23" 743.33
"2009-02-24" 773.14
"2009-02-25"  764.9
"2009-02-26" 752.83
"2009-02-27" 735.09
"2009-03-02" 700.82
"2009-03-03" 696.33
"2009-03-04" 712.87
"2009-03-05" 682.55
"2009-03-06" 683.38
"2009-03-09" 676.53
"2009-03-10"  719.6
"2009-03-11" 721.36
"2009-03-12" 750.74
"2009-03-13" 756.55
"2009-03-16" 753.89
"2009-03-17" 778.12
"2009-03-18" 794.35
"2009-03-19" 784.04
"2009-03-20" 768.54
"2009-03-23" 822.92
"2009-03-24" 806.12
"2009-03-25" 813.88
"2009-03-26" 832.86
"2009-03-27" 815.94
"2009-03-30" 787.53
"2009-03-31" 797.87
"2009-04-01" 811.08
"2009-04-02" 834.38
"2009-04-03"  842.5
"2009-04-06" 835.48
"2009-04-07" 815.55
"2009-04-08" 825.16
"2009-04-09" 856.56
"2009-04-10"      .
"2009-04-13" 858.73
"2009-04-14"  841.5
"2009-04-15" 852.06
"2009-04-16"  865.3
"2009-04-17"  869.6
"2009-04-20" 832.39
"2009-04-21" 850.08
"2009-04-22" 843.55
"2009-04-23" 851.92
"2009-04-24" 866.23
"2009-04-27" 857.51
"2009-04-28" 855.16
"2009-04-29" 873.64
"2009-04-30" 872.81
"2009-05-01" 877.52
"2009-05-04" 907.24
"2009-05-05"  903.8
"2009-05-06" 919.53
"2009-05-07" 907.39
"2009-05-08" 929.23
"2009-05-11" 909.24
"2009-05-12" 908.35
"2009-05-13" 883.92
"2009-05-14" 893.07
"2009-05-15" 882.88
"2009-05-18" 909.71
"2009-05-19" 908.13
"2009-05-20" 903.47
"2009-05-21" 888.33
"2009-05-22"    887
"2009-05-25"      .
"2009-05-26" 910.33
"2009-05-27" 893.06
"2009-05-28" 906.83
"2009-05-29" 919.14
"2009-06-01" 942.87
"2009-06-02" 944.74
"2009-06-03" 931.76
"2009-06-04" 942.46
"2009-06-05" 940.09
"2009-06-08" 939.14
"2009-06-09" 942.43
"2009-06-10" 939.15
"2009-06-11" 944.89
"2009-06-12" 946.21
"2009-06-15" 923.72
"2009-06-16" 911.97
"2009-06-17" 910.71
"2009-06-18" 918.37
"2009-06-19" 921.23
end