Frequencies for first 10,000 rows of mod_year variable in person dataset :

 Model Year |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          1        0.01        0.01
         33 |          1        0.01        0.02
         47 |          1        0.01        0.03
         48 |          3        0.03        0.06
         49 |          8        0.08        0.14
         50 |         11        0.11        0.25
         51 |         10        0.10        0.35
         52 |         11        0.11        0.46
         53 |         10        0.10        0.56
         54 |         20        0.20        0.76
         55 |         21        0.21        0.97
         56 |         27        0.27        1.24
         57 |         46        0.46        1.70
         58 |         17        0.17        1.87
         59 |         46        0.46        2.33
         60 |         58        0.58        2.91
         61 |         60        0.60        3.51
         62 |        114        1.14        4.65
         63 |        170        1.70        6.35
         64 |        227        2.27        8.62
         65 |        295        2.95       11.57
         66 |        392        3.92       15.49
         67 |        421        4.21       19.70
         68 |        550        5.50       25.20
         69 |        616        6.16       31.36
         70 |        625        6.25       37.61
         71 |        549        5.49       43.10
         72 |        723        7.23       50.33
         73 |        890        8.90       59.23
         74 |        829        8.29       67.52
         75 |        612        6.12       73.64
         76 |        932        9.32       82.96
         77 |        646        6.46       89.42
         78 |         22        0.22       89.64
         79 |          4        0.04       89.68
         80 |          1        0.01       89.69
         99 |        153        1.53       91.22
          . |        878        8.78      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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