Not for a long time, in the 80's Marvel was thought to be at 70% but there was no real hard data then. They fell pretty quick in the early 90's and by the time the early 2000's they were second place to DC with things being nearly exactly the opposite of what they are now with DC in the mid 30's and Marvel hovering in the mid 20's, but then in the mid-2000's Marvel took off and DC hasn't been on top since.