Frequencies for additionalcoverageofferedin variable in snp2017 dataset :

 Additional |
   Coverage |
 Offered in |
    the Gap |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      8,032       90.17       90.17
        Yes |        876        9.83      100.00
------------+-----------------------------------
      Total |      8,908      100.00

by Jean Roth , jroth@nber.org , 6 Dec 2016