device: 0.789
graphic: 0.612
network: 0.543
performance: 0.329
files: 0.269
semantic: 0.243
other: 0.209
debug: 0.171
socket: 0.151
boot: 0.146
PID: 0.089
vnc: 0.034
permissions: 0.009
KVM: 0.001

qemu-img manpage and  is missing info on compression_type option