Frequencies for first 10,000 rows of hdl variable in nhamcsopd2011 dataset :

Was high density lipoprotein (HDL) |
    drawn within 12 months of this |
                            visit? |      Freq.     Percent        Cum.
-----------------------------------+-----------------------------------
                             Blank |      2,308       23.08       23.08
Not applicable, provider not asked |        218        2.18       25.26
                               Yes |      1,828       18.28       43.54
       None found within 12 months |      5,646       56.46      100.00
-----------------------------------+-----------------------------------
                             Total |     10,000      100.00

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