Frequencies for ser_tr variable in vehicle dataset :

 VIN SERIES |
      TRUCK |      Freq.     Percent        Cum.
------------+-----------------------------------
        *** |        371       68.20       68.20
        40S |          4        0.74       68.93
        600 |          6        1.10       70.04
        70S |          1        0.18       70.22
        937 |          1        0.18       70.40
        999 |         87       15.99       86.40
        ARO |          2        0.37       86.76
        AST |          1        0.18       86.95
        B20 |          1        0.18       87.13
        B22 |          1        0.18       87.32
        B23 |          2        0.37       87.68
        B25 |          1        0.18       87.87
        B26 |          1        0.18       88.05
        C10 |          1        0.18       88.24
        CHK |          4        0.74       88.97
        COF |          9        1.65       90.63
        CON |          5        0.92       91.54
        CTV |          3        0.55       92.10
        D21 |          1        0.18       92.28
        DRW |          2        0.37       92.65
        ECO |          2        0.37       93.01
        ENV |          1        0.18       93.20
        FRT |          2        0.37       93.57
        GCK |          2        0.37       93.93
        GM4 |          1        0.18       94.12
        HSG |          1        0.18       94.30
        JEE |          3        0.55       94.85
        LIB |          2        0.37       95.22
        MMX |          1        0.18       95.40
        NPR |          1        0.18       95.59
        NRR |          1        0.18       95.77
        OFF |          1        0.18       95.96
        RID |          1        0.18       96.14
        RMV |          1        0.18       96.32
        RNG |          3        0.55       96.88
        RPC |          1        0.18       97.06
          S |          1        0.18       97.24
        SAF |          1        0.18       97.43
        SIE |          1        0.18       97.61
        SIL |          1        0.18       97.79
        SRW |          1        0.18       97.98
        TAC |          4        0.74       98.71
        TUN |          2        0.37       99.08
        VAN |          1        0.18       99.26
        WIN |          2        0.37       99.63
        WRA |          1        0.18       99.82
        XCB |          1        0.18      100.00
------------+-----------------------------------
      Total |        544      100.00

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