Frequencies for first 10,000 rows of injury variable in linkco1991us_num dataset :

      Birth |
     injury |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         38        0.38        0.38
          2 |      8,811       88.11       88.49
          8 |         11        0.11       88.60
          9 |      1,140       11.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015