public function bottomByPercent($num)
    {
        $count = $this->countData();
        return $this->bottom(round($num*$count/100));
    }
public function bottomByPercent($num)
    {
        $count = $this->countData();
        return $this->bottom(round($num*$count/100));
    }
public function bottomByPercent ( $ num ) { $ count = $ this -> countData ( ) ; return $ this -> bottom ( round ( $ num * $ count / 100 ) ) ; }
Return the bottom rows by percent

Example: Return 20% bottom rows
$dataSore->bottomByPercent(20);

@param float $num The number in percent

@return DataStore The new datastore containing result
Return the bottom rows by percent