I assume that I'm included and correctly placed in the CET timezone since I've given my feedback on this already earlier.
Could you maybe publish here, who the two citizens are whose timezones you do not know? Then either they or anyone else with the knowledge could get back to you anonymously or in whatever fashion they prefer to provide a full picture of the distribution.
Furthermore, while we're at the discussion it might be worthwhile to emphasise once more that your location in a specific timezone is only one indicator of what time is most suitable for a meeting requiring your attendance. Other factors influencing one's preferences might be sleeping patterns, office hours, family needs and your ability to create and maintain a time/space-distortion field.