Maybe they mean 1% of the total population of the planet, including non-players.
Maybe they counted NPCs.
Maybe they counted alts.
Maybe they counted all the CO players, none of whom are Admirals.
The real figure is at least 5%. But not much higher than that. If you looked just at the players who all logged on in the past 7 days the percentage would be more like 10-15% but if you take every single account there's no way it will be more than a few decimal points higher than 5%.