Frequencies for ser_tr variable in vehicle dataset :

 VIN SERIES |
      TRUCK |      Freq.     Percent        Cum.
------------+-----------------------------------
            |          3        0.48        0.48
        *** |        424       67.73       68.21
        40S |          4        0.64       68.85
        600 |          7        1.12       69.97
        700 |          1        0.16       70.13
        999 |         97       15.50       85.62
        B20 |          2        0.32       85.94
        B22 |          7        1.12       87.06
        B23 |          1        0.16       87.22
        B25 |          1        0.16       87.38
        B26 |          2        0.32       87.70
        B30 |          3        0.48       88.18
        C10 |          2        0.32       88.50
        C15 |          1        0.16       88.66
        CHK |          4        0.64       89.30
        COF |         14        2.24       91.53
        COM |          1        0.16       91.69
        CON |          4        0.64       92.33
        CSR |          2        0.32       92.65
        CTV |          1        0.16       92.81
        ECO |          1        0.16       92.97
        ENV |          1        0.16       93.13
        GCK |          3        0.48       93.61
        HTP |          1        0.16       93.77
        HUM |          1        0.16       93.93
        MMX |          1        0.16       94.09
        NPR |          1        0.16       94.25
        OFF |          1        0.16       94.41
        P20 |          1        0.16       94.57
        RMV |          1        0.16       94.73
        RNG |          7        1.12       95.85
        RPC |          2        0.32       96.17
          S |          2        0.32       96.49
        S15 |          1        0.16       96.65
        SAF |          2        0.32       96.96
        SIE |          1        0.16       97.12
        SON |          1        0.16       97.28
        SRW |          1        0.16       97.44
        STE |          1        0.16       97.60
        TAC |          3        0.48       98.08
        TRK |          1        0.16       98.24
        TRO |          1        0.16       98.40
        VAN |          7        1.12       99.52
        W/Y |          1        0.16       99.68
        WAG |          1        0.16       99.84
        WRA |          1        0.16      100.00
------------+-----------------------------------
      Total |        626      100.00

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