Frequencies for first 10,000 rows of hdl variable in namcs2011 dataset :

Was high density lipoprotein (HDL) |
  drawn within 12 months of visit? |      Freq.     Percent        Cum.
-----------------------------------+-----------------------------------
                             Blank |      1,588       15.88       15.88
Not applicable, provider not asked |        933        9.33       25.21
                               Yes |      2,095       20.95       46.16
       None found within 12 months |      5,384       53.84      100.00
-----------------------------------+-----------------------------------
                             Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016