How do I change the size of my font when writing a GUI script? I already have this but I don't know how to change the size, can someone help me out?

var fullClip : int = 8;

var bulletsLeft : int = 8;

var reloadTime = 1.5;

function Update () {

if(Input.GetButtonDown("Fire1")){

    if(bulletsLeft > 0 ){

        bulletsLeft -- ;

        }

}



if(Input.GetButtonDown("r")){

    Reload();



}

}

function Reload () {

yield WaitForSeconds(reloadTime);

    bulletsLeft = fullClip ;

}

function OnGUI() {

GUI.Label (Rect (20, 300, 100, 20), ""+bulletsLeft);

}