Could you please help me?
I have to make a school project and I need market information about Arduino Uno board like: date of release (month and year if possible) and pieces sold until now.
The Uno board has undergone 3 design revisions and I can't recall anywhere where they display a release date on hardware designs. Also total production sold is probable not available at all. Your best bet would be to email the arduino co. and ask your questions and see if they respond with anything useful for you.
Keep in mind that there is a whole 3rd party 'clone' manufacture industry and sell all sorts of arduino boards, so the total number of arduino compatible boards sold work wide would be a much higher number then just from arduino co.