It has varied considerably even while living at or near sea-level.
Since about 1980, every year, I have had at least one blood analysis done and I have tried to do it on different months.
When out of shape - end of winter - my Hct has been as high as 46.2 %, but still with only 14.9 g/l.
When in great shape, in summer, as low as 38% with 12.8 g/l.
Which means that properly doped up with EPO I could have been in my late forties climbing at 1650 m/h (for 30 min) instead of 1250 m/h on 7%
A few years ago i started eating black chocolate regularly ( 20 g/day) as my iron values always tended to be low and I don't want to eat too much red meat. In the past 3 years, end of spring, my Hct has been around 45%, but then I don't exhaust myself on the bike as I used to (age, you know, well past 70).
50 years ago, when I lived at an average weekly altitude of 4500 m, I probably approached 55%, unfortunately not confirmed by an analysis.