There are 86,400 seconds in a day. 138KB x 86400/5 = 238640KB /day = ~2328 MB/day = 69,840 MB/month = 67 GB/month. I'm going to go on a limb and say his 138KB

There are 86,400 seconds in a day. 138KB x 86400/5 = 238640KB /day = ~2328 MB/day = 69,840 MB/month = 67 GB/month. I'm going to go on a limb and say his 138KB is more like 1.38KB which would bring us closer to his 0.71 GB/month