OnTriggerEnter2D is being called multiple times....

I’m new to Unity so sorry in advance if this is a basic question, I attached a variable that should add by 1 every time OnTriggerEnter2D is triggered. It however is not adding by 1 but adding constantly. Can please tell me what I’m doing wrong?

Here is where I’m calling it

public class MonsterTarget : MonoBehaviour {
    public Resetter Resetting;
    public ScoreCount ScoreHit;
    public float targetHit = 0;
 
    
	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
	
	}

    public void OnTriggerEnter2D(Collider2D col)
    {
        targetHit ++;
        Resetting.Reset();
        
    }
}

and this is where its going

public MonsterTarget monTarget;

    public Text scoreText;
    public Text highScoreText;

    public float scoreCount;
    public float highScoreCount;

    public bool scoreIncreasing;

	// Use this for initialization
	void Start () {
	    if(PlayerPrefs.HasKey("HighScore"))
            {
            highScoreCount = PlayerPrefs.GetFloat("HighScore");
        }
	}
	
	// Update is called once per frame
	void Update () {
        if (scoreIncreasing)
        {
            scoreCount += monTarget.targetHit;//RIGH HERE IS WHERE IM CALLING IT
        }

        if (scoreCount > highScoreCount)
        {
            highScoreCount = scoreCount;
            PlayerPrefs.SetFloat("HighScore", highScoreCount);
        }

        scoreText.text = "Score: " + Mathf.Round(scoreCount);
        highScoreText.text = "High Score: " + Mathf.Round(highScoreCount);

    }
}

@Bonfire Boy Thank you so much! It was fixed after i changed “+=” to “=”