Frequencies for p4 variable in miper dataset :

         p4 |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |        666       70.40       70.40
          1 |          1        0.11       70.51
          2 |         10        1.06       71.56
          3 |          8        0.85       72.41
          4 |         10        1.06       73.47
          5 |         10        1.06       74.52
          6 |          5        0.53       75.05
          7 |         12        1.27       76.32
          8 |          7        0.74       77.06
          9 |          8        0.85       77.91
         10 |         12        1.27       79.18
         11 |         11        1.16       80.34
         12 |         11        1.16       81.50
         13 |         15        1.59       83.09
         14 |         11        1.16       84.25
         15 |         13        1.37       85.62
         16 |         10        1.06       86.68
         17 |          9        0.95       87.63
         18 |         13        1.37       89.01
         19 |         13        1.37       90.38
         20 |         14        1.48       91.86
         21 |          8        0.85       92.71
         22 |          1        0.11       92.81
         23 |         10        1.06       93.87
         24 |          9        0.95       94.82
         25 |          6        0.63       95.45
         26 |          6        0.63       96.09
         27 |          3        0.32       96.41
         28 |          3        0.32       96.72
         29 |          6        0.63       97.36
         30 |          3        0.32       97.67
         31 |          2        0.21       97.89
         32 |          5        0.53       98.41
         33 |          4        0.42       98.84
         34 |          3        0.32       99.15
         35 |          3        0.32       99.47
         36 |          1        0.11       99.58
         39 |          2        0.21       99.79
         40 |          2        0.21      100.00
------------+-----------------------------------
      Total |        946      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016