I'm not surprised; in SLRs at least, Canon was never the dominant film camera company with the biggest customer base. Their SLR business did not catch up to and pass Nikon until the digital era. Canon's decision to put the AF motor in the lens helped them in verticals that use huge telephotos (sports, mostly). But their film cameras lagged Nikon in the sophistication of their AF, their automated exposure control, and…
What lead are you talking about? Canon's sensors were a running joke in the past 5 years comparing to Nikon (that used modified Sony sensors), manufactured in 3 generation-older process than their competition. Seeing e.g. D750 vs 5D MkIII in low-light was an eye opener. The only selling point of Canon remained their unique "pleasant" color mapping (and photographers getting stuck with older Canon-only lenses/strobes…
Market share. The estimates I've seen are that between Canon, Nikon, and Sony DSLRs, Canon currently has the largest single share of the market.
Prior to Canon's work with CMOS sensors in the early 2000s, Nikon had the SLR and DSLR market share lead over Canon. (And basically no Sony bodies at all back then.)