I cannot figure this out.

I need a solution to call a random function for it's percent.

Ex. there is 10% chances that the script calls subscriptions() and 3% chance that the system call the function "specialitems()".

I am stuck in this, so i hope someone can help me with this brainkiller.

<?php
   class RandomGifts {
   public $chances = '';

   public function __construct($user) {
          $this->user = $user;

          //Find percent for each function
          $this->chances = array( 
                 'subscriptions' => 10, // 10%
                 'specialitems'  => 3,  //  5%
                 'normalitems'   => 30, // 40%
                 'fuser'         => 50, // 70%
                 'giftcards'     => 7,  //  7%
          );

 //This should call the function which has been calculated.
 self::callFunction(?);

 }

   public function subscriptions(){}
   public function specialitems(){}
   public function normalitems(){}
   public function fuser(){}
   public function giftcards(){}

}
?>