On Sun, 27 Sep 2015 19:29:09 -0700 (PDT), wrote:

Sorry, I should have described more.
These lights are in 4 separate areas/rooms of the basement, on 4 separate switches. Approx 6 lights per room/switch.


The code says you will be fine, general lighting circuits in the US
are based on square footage, not the number of outlets.
YMMV in the great white north.

If you think you would ever have all 75w lamps and all of them will be
on at once, by all means go with the 20a circuit but that is a design
decision not a code decision.