16Gbit is way too little, intra HK traffic is 50Mbit.
http://www.cuhk.edu.hk/hkix/stat/agg...aggregate.html
So what guys do we use more intra HK than browsing outside HK? That 16Gbit is not just for HK people. Tone of ISPs Asia wide peer in HK exchange traffic or transit to US, Europe, Japan. Then there is a pile of MPLS which we are probably not seeing in the HKIX MRTG graph which is transitting through Hong Kong. All the traffic coming in, going out has to be going through some circuits, that are not being accounted here.
I forgot to also mention that there are more Satellite ISPs emerging in HK and I doubt those guys are going talking to Computer world.