Install rpi-monitor to show wifi stats.md

Add RPi-Monitor into repository list:

sudo wget http://goo.gl/vewCLL -O /etc/apt/sources.list.d/rpimonitor.list

Install public key to trust RPi-Monitor repository:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 2C0D3C0F 

Update and install RPi-Monitor:

sudo apt-get update
sudo apt-get install -y rpimonitor

Upgrade RPi-Monitor:

sudo apt-get update
sudo apt-get upgrade

Update information about upgradable packages:

sudo /etc/init.d/rpimonitor update

Edit network.conf to show wifi only:

sudo nano /etc/rpimonitor/template/network.conf

Change the file to:

########################################################################
# Graph WLAN
########################################################################
dynamic.17.name=wifi_received
dynamic.17.source=/sys/class/net/wlan0/statistics/rx_bytes
dynamic.17.regexp=(.*)
dynamic.17.postprocess=$1*-1
dynamic.17.rrd=DERIVE

dynamic.18.name=wifi_send
dynamic.18.source=/sys/class/net/wlan0/statistics/tx_bytes
dynamic.18.regexp=(.*)
dynamic.18.postprocess=
dynamic.18.rrd=DERIVE

web.status.1.content.9.name=WiFi
web.status.1.content.9.icon=wifi.png
web.status.1.content.9.line.1="WiFi Sent: <b>"+KMG(data.wifi_send)+"<i class='icon-arrow-up'></i></b> Received: <b>"+KMG(Math.abs(data.wifi_received)) + "<i class='icon-arrow-down'></i></b>"

web.statistics.1.content.9.name=WiFi
web.statistics.1.content.9.graph.1=wifi_send
web.statistics.1.content.9.graph.2=wifi_received
web.statistics.1.content.9.ds_graph_options.net_send.label=Upload bandwidth (bits)
web.statistics.1.content.9.ds_graph_options.net_send.lines={ fill: true }
web.statistics.1.content.9.ds_graph_options.net_send.color="#FF7777"
web.statistics.1.content.9.ds_graph_options.net_received.label=Download bandwidth (bits)
web.statistics.1.content.9.ds_graph_options.net_received.lines={ fill: true }
web.statistics.1.content.9.ds_graph_options.net_received.color="#77FF77"