On the "statistics" front you need more data. The monthly numbers for the months May to April at a minimum. Better the same numbers from the previous year.
BTW, could you explain the second number 70.6% in "php Hits=2,983,758 70.6 % Bandwidth=56.72 GB approximately 160kb per php hit"? Also, what are the tool and the method which give you these numbers?
On the network traffic side, there is no tool in the core to measure the traffic each learning material or activity has caused. If you have all the logs, it might be possible with a custom reporting tool. Check with the people doing Analytics and reporting https://moodle.org/mod/forum/view.php?id=8044.