Academics 
~ None; That's what research students are for. 
~ Five; One to write the grant proposal, one to do the mathematical modeling, one to type the research paper, one to submit the paper for publishing, and one to hire a student to do the work. 

Accountants 
~ What answer did you have in mind? 

Actors 
~ Twenty; one to 'phone for an Expert, one to propose a toast to the new bulb. And 18 to say what a lousy bulb the old one was. 
~ Two. One to stand on a chair to change it, one to say "I wish I was up there!" 
~ One. They don't like to share the spotlight 
~ One, but 462 auditioned for the part. 

Aerobics instructors 
~ Two; one to do it in perfect synchrony(!) while the other one calls "To the left, and to the left, and to the left, and to the left, and take it out, and put it down, and pick it up, and put it in, and to the right, and to the right, and to the right, and to the right..." 

Anarchists 
~ All of them; each must do for theirself. 

Anglers 
~ Two, and you should've seen the light bulb! It must have been this big! 

Archaeologists 
~ Three. One to change it while the other two argue about how old the old one is. 

Art Gallery visitors 
~ Two, one to do it and one to say "My four-year old could do better than that". 

Astronomers 
~ None, astronomers prefer the dark. 

Atheists 
~ None. Atheists never see the light. 

Auctioneers 
~ One ... two ... three ... any advance on three? 

Auto mechanics 
~ Three; one to screw in all the bulbs he has until he finds one that fits, one to make sure you get to pay for them all and another to tell you he thinks he'll have to replace the whole socket. 

Baby Boomers 
~ Eleven; four to talk about how great it is that they've all come together to do this, one to screw it in, one to video it for next year's reunion, one to film it for the news, one to plan a marketing strategy based on it, one to reminisce about mass naked bulb screwings-in in the '60s, one to watch reruns of '50s TV shows, and one to play classic rock. 

Backstage crew 
~ Eight. One person to get the scaffolding out, erect the scaffolding tower, isolate the power supply, take the blown lamp out, find a replacement, stick it in, reset the fuses, turn the power back on, climb up the tower, refocus the light, take the scaffolding tower down and put it away. The other seven sit in the control room, supervise, and broadcast helpful comments over the tannoy. 

Big black 1 x 4 x 9 monoliths 
~ 2001 

Bosses 
~ None, they like to keep employees in the dark. 

Brewers 
~ About one third less than for a regular bulb. 

Building subcontractors 
~ It takes 47; one to hold the bulb, 46 to turn the house around. 

Bureaucrats 
~ 45. One to change the bulb, and 44 to do the paperwork. 

Burger King adverts 
~ None. "I can't change my lightbulb. But I can change my burger to a Burger King burger." 

Californians 
~ Six. One to turn the bulb, one for support, and four to relate to the experience. 

Canadians 
~ Two; one to change it, one to spray green paint on to the new bulb so no-one bashes it with a big stick. 

Cashiers 
~ Are you kidding? They won't even change a five dollar bill. 

Chickens 
~ Two; one to do it and one to cross the road. 

Chiropractors 
~ Only one. But it takes nine visits. 

Circus performers 
~ Four. One to change the bulb and three to go: "Ta da!" 

College students 
~ Dunno, I forgot my calculator. 

College football players 
~ Just one -- and he gets three credits for it! 

Computer journalists 
~ Fifty-four; Fifty to write boring reviews of all the existing light bulbs, all concluding that Microsoft is best, one to write a remarkably similar review in a broadsheet the next month, another to have a big one come out in a sunday paper paper two months later (by then completely out of date), another to hint in that a completely new and updated bulb is coming out, and the fifty-fourth to report a rumor that the new bulb is shipping with a virus. 

Computer programmers 
~ Two; one always leaves in the middle of the project. 
~ None. That's a hardware function. 

Conservatives 
~ Three; one to deny that it's gone out, one to say that it's burning more brightly than under any previous Labour government and one to change it while no-one's looking. 

Consultants 
~ I'll have an estimate for you a week from Monday. 

Darwinians 
~ None; light bulbs are an evolutionary dead end. 

Dentists 
~ Three. One to administer the anaesthetic, one to extract the lightbulb, and one to offer the socket some vile pink mouthwash. 

Do It Yourself buffs 
~ One. But it takes two weekends and three trips to the hardware store. 

Doctors 
~ None; they just tell it to take two aspirin and get plenty of rest. 
~ One; but he needs a nurse to tell him which end to screw in. 
~ Two; one to change the bulb and one to sign the death certificate. 
~ Three; one to diagnose the problem, one to prescribe a new bulb ... and one to watch the nurse change it 

Drinkers (serious drinkers) 
~ Twenty-one; one to hold the bulb and 20 to drink until the room spins. 

Drummers 
~ Five; one to do it and four to beat back all the guitarists who are trying to elbow their way into the spotlight. 

Dull people 
~ One. 

Dylan fans 
~ The answer, my friend, is blowin' in the wind. The answer is blowin' in the wind. 

Editors 
~ Two; one to change the bulb and one to issue a rejection slip to the old bulb. 

Efficiency experts 
~ does it take to replace a light bulb? None. Efficiency experts replace only dark bulbs. 

Einsteins 
~ One-ish; it depends on the speed of the changer, and the mass of the bulb. Or vice versa, of course. Then it just might be easier to leave the bulb alone and change the room. It's all relative. 

Elvis fans 
~ None. They will never find another bulb that burns as brightly as the old one.