Except, of course the average day, in reality, rarely exists and other factors come into play.
Start with the weight, then the temperature, the pressure, any runway slope, wind speed and direction, altitude of the runway and any variables the airline ops manual may throw in for the particular runway.
Nowadays the computer does it all, back in the 1970s it was a set of graphs and a circular slide rule....happy days.
When I used to fly CX to HKG a fair bit, they used to have their 'air show' running during take-off at AKL. Pretty much every time, the ground speed was ~200kts at rotation. This was for a 742 by the way.
I'm well aware of all the factors you have to take into account to calculate take off speed. However, there are fairly consistent knots indicated airspeed velocities for an aircraft at full weight. It doesn't vary that much with temperature and altitude. All I'm looking for here is a rough estimate for the rotation velocity of fully loaded 764 at sea level and 70 degrees absent winds give or take a few kias. Why you gotta be so picky and technicl all the time?