Explicit Proxy Statistics

I've been requested to provide traffic statistics for our Explicit Web Proxy.

So far, the only thing I can come up with is

1500D (vdom1) # diagnose wad history list all 30days

:

stats history vd=1 proto=webproxy period=last 30day                --- LAN ---                               --- WAN ---       bytes_in             bytes_out            bytes_in             bytes_out     ------------         -------------        ------------         -------------      1210963763          52012257756          51987229581           1164679599      1471630933          58194609629          58142345469           1377421801      1119711506          52142533366          52109647494           1050307704       703493989          28314785975          28267540034            625399492       587175995          10862914785          10832729557            522582123

:

Using Wireshark, I think I can match above bytes as L7 payload within ingress/egress packets.

Is this indeed accurate Web Proxy usage stats? Is there some other way to get Web Proxy stats out of the Fortigate?