laravel 5.1 using middleware to measure datasize of incoming and outgoing request

i am trying to measure the data size of all incoming and out going request using a middleware in laravel. This will help me know the internet data my application is using. the problem is that i cannot get access to data being sent from my server to the client or browser and i think it is because i am new to laravel. if using a middleware is not possible , an event would also be appreciated although i have a lot of routes thereby making the "events" a tedious process. When i log the log the request, i don't get the data i want. how to get the size of the data into kilobytes will also be helpful.

<?php

namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Response;
use Log;


class MeasureDataSizeMiddleware
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        return $next($request);
    }

    public function terminate($request, $response)
    {
// measure the size
    //store the data into a database of incoming and outgoing request.
     //Log::info('app.requests', ['request' => $request, 'response' => new Response($response)]);

       }
    }

via Chebli Mohamed