Spawning random enemies in spawn points

I have side scrolling game (almost) and I have a little problem with enemy spawnig. I already have spawn points located on map and whenever my BGLooper collides with spawn point it's gonna move forward, next to last spawn point. I can't figure how to spawn 1 of my 8 enemies in each spawnpoint randomly. Any ideas?

 using UnityEngine;
 using System.Collections;
 
 public class BGLooper : MonoBehaviour {
 
     int numBGPanels = 6;
 
     float minEnemy = 1;
     float maxEnemy = 8;
     
 
     void OnTriggerEnter2D(Collider2D collider) {
         Debug.Log ("Triggered: " + collider.name);
 
         float widthOfBGObject = ((BoxCollider2D)collider).size.x;
         
         Vector3 pos = collider.transform.position;
         
         pos.x += widthOfBGObject * numBGPanels;
 
         collider.transform.position = pos;
 
         if (collider.tag == "Enemy") {
 
 
                 }
     }
 }