while (my $series = shift @series) {
   my $nums = shift @series;
   $empwork{$series}{TTL} += $nums;
   $empwork{$series}{CNT}++;
}

##</code><code>##

for my $empnum (sort keys %empwork) {
   ...
   my $periods = $empwork{$empnum}{CNT};
   ...
}