use 5.010;

my @headers = do { chomp($_ = <DATA>); split /\t/ };

while (<DATA>)
{
	chomp;
	
	my %F; @F{@headers} = split /\t/;
	
	say $F{'N Total Depth'};
}

__DATA__
Non-Syn	Splice	dbSNP	N (Var Depth)	N Total Depth	N Freq	T (Var Depth)
1	0	0	0	34	0	11
1	0	0	0	54	0	14
1	0	0	0	42	0	11