How to have multiple enemies spawn in a wave?

So I have a wave spawner script that has only one slot available for something, in this an enemy. I tried messing with my script to include multiple enemies in one wave, but to no success. Below is my current script that anyone can use. It is a bit long, but I decided to include all of it because I wanted anyone to use it.

public class WaveSpawner : MonoBehaviour {

 public enum SpawnState { SPAWNING, WAITING, COUNTING };

 [System.Serializable]
 public class Wave
 {
     public string name;
     public Transform enemy;
     public int count;
     public float rate;
 }

 public Wave[] waves;
 private int nextWave = 0;

 public Transform[] spawnPoints;

 public float timeBetweenWaves = 5f;
 public float waveCountdown;

 private float searchCountdown = 1f;

 private SpawnState state = SpawnState.COUNTING;

 void Start()
 {
     if (spawnPoints.Length == 0)
     {
         Debug.LogError("Now spawn points referenced.");
     }

     waveCountdown = timeBetweenWaves;
 }

 void Update ()
 {
     if (state == SpawnState.WAITING)
     {
         if (!EnemyIsAlive())
         {
             WaveCompleted();
         }
         else
         {
             return;
         }
     }

     if (waveCountdown <= 0)
     {
         if (state != SpawnState.SPAWNING)
         {
             StartCoroutine(SpawnWave(waves[nextWave]));
         }
     }
     else
     {
         waveCountdown -= Time.deltaTime;
     }
 }

 void WaveCompleted ()
 {
     Debug.Log("Wave Completed!");

     state = SpawnState.COUNTING;
     waveCountdown = timeBetweenWaves;

     if(nextWave + 1 > waves.Length - 1)
     {
         //When all waves are complete!
         nextWave = 0;
         Debug.Log("ALL WAVES COMPLETE! Looping...");
     }
     else
     {
         nextWave++;
     }
 }

 bool EnemyIsAlive ()
 {
     searchCountdown -= Time.deltaTime;
     if (searchCountdown <= 0f)
     {
         searchCountdown = 1f;
         if (GameObject.FindGameObjectWithTag("Enemy") == null)
         {
             return false;
         }
     }
     return true;
 }

 IEnumerator SpawnWave (Wave _wave)
 {
     Debug.Log("Spawning Wave: " + _wave.name);
     state = SpawnState.SPAWNING;

     for (int i = 0; i < _wave.count; i++)
     {
         SpawnEnemy(_wave.enemy);
         yield return new WaitForSeconds(1f / _wave.rate);
     }

     state = SpawnState.WAITING;

     yield break;
 }

 void SpawnEnemy (Transform _enemy)
 {
     Debug.Log("Spawning Enemy: " + _enemy.name);

     Transform _sp = spawnPoints[Random.Range(0, spawnPoints.Length)];
     Instantiate(_enemy, _sp.position, _sp.rotation);
 }

}

Thanks, and I will be as clear as possible.