For each task, display the total swap usage as a percent of total
memory.

Task name             PID          RSS in kB         SWAP in kB   ADJ
procrank             4809      133,476(2.3%)            0(0.0%) -1000
main                  707       50,736(0.9%)       17,552(0.3%) -1000

Change-Id: I583cd219918e3c27a9447a39b6ba459f25c44566