MouseWheel Lerp Smoothing Problem

In below code, smoothing works very well with X and Y axises (w-a-s-d), but somehow i can not smooth the zoom in and out (z axis, mouse wheel) with this code. What am i doing wrong? Thanks in advance.

 public float cameraMultiplierX, cameraMultiplierY, cameraMultiplierZ, cameraSmoothness;
 private float camX, camY, camZ;
     
 void Start () 
 {
     camX = 0;
     camY = 0;
     camZ = 0;
 }
 
 void Update()
 {
     Vector3 finalMovement = Vector3.zero;
 
     /* -- Raw inputs -- */
     float rawX = Input.GetAxis ("Horizontal") * cameraMultiplierX;
     float rawY = Input.GetAxis ("Vertical") * cameraMultiplierY;
     float rawZ = Input.GetAxis ("Mouse ScrollWheel") * cameraMultiplierZ;
         
     /* -- Lerps -- */
     camX = Mathf.Lerp (camX, rawX, cameraSmoothness * cameraMultiplierX);
     camY = Mathf.Lerp (camY, rawY, cameraSmoothness * cameraMultiplierY);
     camZ = Mathf.Lerp (camZ, rawZ, cameraSmoothness * cameraMultiplierZ);
         
     /* -- Final application -- */
     finalMovement = new Vector3 (camX, camY, camZ);
 
     mainCamera.transform.Translate(finalMovement * Time.deltaTime);
 }