Frequencies for pser_tr variable in parkwork dataset :

  vin truck |
     series |      Freq.     Percent        Cum.
------------+-----------------------------------
            |        636       58.30       58.30
        20S |          2        0.18       58.48
        30S |          2        0.18       58.66
        4/5 |          1        0.09       58.75
        40S |         17        1.56       60.31
        44P |          1        0.09       60.40
        600 |          6        0.55       60.95
        70S |          2        0.18       61.14
        80S |          1        0.09       61.23
        90S |          2        0.18       61.41
        920 |          2        0.18       61.59
        940 |          1        0.09       61.69
        990 |          1        0.09       61.78
        AVL |          2        0.18       61.96
        B23 |          4        0.37       62.33
        B25 |          1        0.09       62.42
        BSR |          1        0.09       62.51
        C/C |          1        0.09       62.60
        C10 |          1        0.09       62.69
        C20 |          2        0.18       62.88
        C55 |          2        0.18       63.06
        C65 |          1        0.09       63.15
        C75 |          1        0.09       63.24
        CAL |          4        0.37       63.61
        CAR |          9        0.82       64.44
        CCH |          1        0.09       64.53
        CHA |          2        0.18       64.71
        CHK |          4        0.37       65.08
        CMP |          1        0.09       65.17
        CNV |          1        0.09       65.26
        COF |         41        3.76       69.02
        CON |         42        3.85       72.87
        CSC |          8        0.73       73.60
        CSR |          4        0.37       73.97
        CTV |          5        0.46       74.43
        D30 |          1        0.09       74.52
        DAK |          6        0.55       75.07
        DEN |          1        0.09       75.16
        DIS |          1        0.09       75.25
        DRW |         11        1.01       76.26
        ECO |          1        0.09       76.35
        ENV |          4        0.37       76.72
        ETV |          1        0.09       76.81
        EXP |          3        0.27       77.09
        FM2 |          3        0.27       77.36
        FM6 |          1        0.09       77.45
        FRT |          4        0.37       77.82
        GCK |          7        0.64       78.46
        GM4 |         10        0.92       79.38
        HIN |          3        0.27       79.65
        HTP |          8        0.73       80.38
        HUM |          1        0.09       80.48
        LIB |          7        0.64       81.12
        MCV |          2        0.18       81.30
        MHV |          2        0.18       81.48
        NQR |          1        0.09       81.58
        P30 |          1        0.09       81.67
        PRO |          6        0.55       82.22
        RMV |          3        0.27       82.49
        RNG |         12        1.10       83.59
        RPC |         26        2.38       85.98
        RRV |          1        0.09       86.07
        RSP |          1        0.09       86.16
          S |          6        0.55       86.71
        S/V |          1        0.09       86.80
        SAF |          2        0.18       86.98
        SAV |          2        0.18       87.17
        SIE |         21        1.92       89.09
        SIL |         30        2.75       91.84
        SON |          2        0.18       92.03
        SRW |         17        1.56       93.58
         SS |          1        0.09       93.68
        STE |          3        0.27       93.95
        STV |          1        0.09       94.04
        TAC |          7        0.64       94.68
        TOP |          1        0.09       94.78
        TRK |          1        0.09       94.87
        TSP |          1        0.09       94.96
        TSR |          2        0.18       95.14
        TTN |          2        0.18       95.33
        TUN |          8        0.73       96.06
        TWC |          6        0.55       96.61
        UDS |          1        0.09       96.70
        VAN |          8        0.73       97.43
        VOF |          2        0.18       97.62
        VTR |          4        0.37       97.98
        VVN |          8        0.73       98.72
        W/T |          3        0.27       98.99
        W/Y |          1        0.09       99.08
        WCN |          1        0.09       99.18
        WIN |          4        0.37       99.54
        WRA |          2        0.18       99.73
        WUL |          1        0.09       99.82
        XPD |          1        0.09       99.91
        YUK |          1        0.09      100.00
------------+-----------------------------------
      Total |      1,091      100.00

by Jean Roth , jroth@nber.org , 22 Oct 2016