A visual of YYZ's dominance using G.S's list:
www.gcmap.com
Data (didn't bother removing duplicates): yyz-dub, yyz-ams, yyz-pek, yyz-bog, yyz-eze-scl, yyz-cph, yyz-del, yyz-dxb, yyz-fra, yyz-gva, yyz-hkg, yyz-ist, yyz-lhr, yyz-mad, yyz-mxp, yyz-muc, yyz-gig, yyz-fco, yyz-gru, yyz-icn, yyz-pvg, yyz-yvr-syd, yyz-tlv, yyz-hnd, yyz-nrt, yyz-zrh, yyz-ath, yyz-bcn, yyz-bud, yyz-dub, yyz-edi, yyz-gla, yyz-lim, yyz-lis, yyz-lgw, yyz-man, yyz-prg, yyz-vce, yyz-waw, yyz-cdg, yyz-fco, yyz-vie, yyz-lhr, yyz-hkg, yyz-pvg, yyz-fra, yyz-cai, yyz-tlv, yyz-dxb, yyz-add, yyz-auh, yyz-tpe, yyz-pek, yyz-rkv, yyz-lhr-del, yyz-ams, yyz-icn, yyz-waw, yyz-fra, yyz-muc, yyz-isb, yyz-khi, yyz-mnl, yyz-lis, yyz-pdl, yyz-ter, yyz-jed-ruh, yyz-ist, yyz-lgw