Hello, I have created a table of multiple-choice questions and I want to generate a variable of a single value. In this case, the 11. How could I do it? (Stata 14)

Code:
 mrtab C1a-C1c, poly response(1/30)

            |             Percent of     Percent
            |  Frequency   responses    of cases
------------+-----------------------------------
          1 |        185       15.11       41.76
          2 |         24        1.96        5.42
          3 |          6        0.49        1.35
          4 |         93        7.60       20.99
          5 |        151       12.34       34.09
          6 |          8        0.65        1.81
          7 |         18        1.47        4.06
          8 |        103        8.42       23.25
          9 |        132       10.78       29.80
         10 |         60        4.90       13.54
         11 |         88        7.19       19.86
         12 |         19        1.55        4.29
         13 |         50        4.08       11.29
         14 |         32        2.61        7.22
         15 |          8        0.65        1.81
         16 |         19        1.55        4.29
         17 |          4        0.33        0.90
         18 |         17        1.39        3.84
         19 |         24        1.96        5.42
         20 |          9        0.74        2.03
         21 |         10        0.82        2.26
         22 |         18        1.47        4.06
         23 |         11        0.90        2.48
         24 |         22        1.80        4.97
         25 |          7        0.57        1.58
         26 |         19        1.55        4.29
         27 |         16        1.31        3.61
         28 |         33        2.70        7.45
         29 |          5        0.41        1.13
         30 |         33        2.70        7.45
------------+-----------------------------------
      Total |       1224      100.00      276.30