public class PlayerStats : MonoBehaviour {
float dispPlayerHealth;
public Transform player;
public Rect rectangle = new Rect(0,0,50,25);
string boxText = string.Empty;
void Update () {
    Vector3 screenPosition = Camera.current.WorldToScreenPoint( player.position );
    rectangle.x = screenPosition.x;
    rectangle.y = screenPosition.y;
    float playerHealthNow = GetComponent<MoveCharacter>().playerHealth;
    if(dispPlayerHealth != playerHealthNow) { dispPlayerHealth = playerHealthNow; boxText = string.Format("{0:0}", dispPlayerHealth); }
}

void OnGUI (){
    GUI.Box(rectangle, boxText);
}
}