Calculating clicks per minute based on mouse clicks. Needed to calculate something for my game

Calculating Clicks per minute

if (e.type == MouseEvent.MOUSE_DOWN)
{	
	if (last_dt == 0) //first time. no avg yet.
	{
		last_dt = getTimer();
	}
	else
	{
		if (new_dt == 0)	//second time, first cps, first average
		{
			data_count++;
			new_dt = getTimer();
			average_dt = 60000 / (new_dt - last_dt);
			
			sum += average_dt;
		}
		else
		{
			data_count++;
			new_dt = getTimer();
			
			//latest clicks per sec calculation
			cps = 60000 / (new_dt - last_dt);
			
			//new average
			average_dt = (average_dt * (data_count-1)/data_count) + (cps/data_count);
		}
		
		debug_tf.text = Math.round(average_dt) + "";
		last_dt = new_dt;
	}
}

******* var declarations ******

private var debug_tf:TextField = new TextField();
private var last_dt:Number = 0, new_dt:Number = 0, cps:Number = 0;
private var average_dt:Number = 0, data_count:Number = 0, sum:Number = 0;