Frequencies for additionalcoverageofferedint variable in snp2015 dataset :

     Additional |
       Coverage |
 Offered in the |
            Gap |      Freq.     Percent        Cum.
----------------+-----------------------------------
             No |      7,971       90.93       90.93
No Gap Coverage |          1        0.01       90.94
            Yes |        794        9.06      100.00
----------------+-----------------------------------
          Total |      8,766      100.00

by Jean Roth , jroth@nber.org , 14 Apr 2016