What % would you suggest for the other (earlier) eras ?
Since very few societies took censuses and the numbers of men even in individual battles is frequently Wild Guesses on the part of some chronicler who wasn't there, it's hard to come up with 'hard' figures. Here are some indicators, though:
1. The Roman Empire had a population of at least 50,000,000, and possibly as much as 100,000,000, but the Roman military, even counting barbarian auxiliaries, never exceeded 500,000. That means, even with a fairly sophisticated infrastructure and very good 'industrial' base to provide weapons and equipment (they had virtual factories n northern Italy turning out legionary armor and weapon) they barely mobilized 1% of the total population.
2. In 9th - 11th century CE Saxon England, every 5 families was supposed to provide one infantryman for the Fyrd, equipped with a shield and spear - no armor, no metalworking-heavy swords or helmets, and of course a 'family' has to be considered to be at least 4 - 7 men, women and children each. That's about 20%, but it was only from families that worked land (admittedly, the majority of the population at the time), and not particularly well equipped, and they could only be 'called up' for a maximum of 60 days a year (which is why Harold's Army at Hastings was missing most of the Great Fyrd - he had to send them home)
3. In the High Years of the French Empire 1805 - 1811, Napoleon had upwards of 1,000,000 men in uniform out of a French population of a little less than 30,000,000. However, a large percentage of the troops were not French: the total included units raised from Dutch, Belgian, German, and Italian populations under French control, and the 500,000 man force that went into Russia in 1812 was only about half French: it also included just over 150,000 Austrian and Prussian 'allied' troops plus contingents of Germans, Poles, Dutch, etc. And, of course, the total was not sustainable: by 1813 a combination of war weariness and economic strains at home were making it very difficult to get any more troops out of France, and 'draft dodging' was reaching the point where 2 out of every 3 men called up failed to report.
4. The population of the Athenian Demes in the classical period (around 450 BCE) has been estimated at just under 500,000 (and this may be wildly off: the Athenians even when they did count people, never counted slaves and women!). Athens never put more than 10,000 hoplites into the field, but at its height her navy had a little over 200 ships with about 45,000 crewmen. Of course, 'crewmen' were mostly rowers who didn't have to provide any equipment, while a hoplite had to provide his own armor, spear, helmet, and shield.
Overall, then, and this is based on few hard figures and a lot of 'SWAG" ("Scientific Wild-A** Guessing") I would estimate that most Ancient to Renaissance Era societies could regularly put 1% of the total population into the military, but possibly as many as 6 - 10% IF they didn't have to be well-equipped - no fancy metalwork, swords, armor, etc - And the higher figures could not be kept away from the economy for more than a fraction of the year unless Someone Else was providing food for the rest of the population - Athen's navy was being fed with imported grain from the Greek cities along the Black Sea coast and North Africa, for example.