Från internet:
If you don't need it real time, there is a way...
In terminal:
ping -i 2 -c 100 bbc.co.uk > pings.txt
That's 100 pings at 2 second intervals, modify to suit.
This will put pings.txt into the root of your home folder, open it and copy/paste special the contents into a spreadsheet (eg in NeoOffice). Process as required
Mac ping plotter