Output from vcftools missingness I'm new to data filtering on vcf data and vcftools.
I performed variant calling on my dataset, CHR22, homo sapiens. I'd like to remove sites that are missing in more than 5% of individuals.  

vcftools --missing-site --vcf updated_ids68.vcf


 

This gives me a file with out.lmiss. That is missingness per locus.
I had 68 individuals in my input vcf file.

CHR     POS     N_DATA  N_GENOTYPE_FILTERED     N_MISS  F_MISS  
22      16848278        106     0       30      0.283019  
22      16848492        68      0       68      1  
22      16849180        69      0       67      0.971014  
22      16849229        68      0       68      1  
22      16849376        133     0       3       0.0225564  
22      16849476        132     0       6       0.0454545  
22      16851734        126     0       36      0.285714  
22      16852588        123     0       13      0.105691


 

I'm unable to understand the output here. What does third column - N_DATA tell?
133, 126 doesn't tell that this is number of individuals if my input had 68 individuals only.  

VCFtools (0.1.15)
fileformat=VCFv4.1
Humans are diploid, so you can expect to see up to 2*N (2*68=136) alleles, so N_DATA is the number of observances of that allele.