Most of the wine sold in the U.S. is done so in 750ml bottles with a cork enclosure. I would give an exact percentage, but once again Finn the black lab, my fact checker, is taking a nap (Finn is awake about 2 hours a day). Just take my word for it based on traveling around the country and spending an inordinate amount of time in retail stores selling wine.
Most people outside (and some inside) the wine business have a romanticized view of what this business is all about. Most things look different when you are an audience member. Once you go behind the curtain, you can become extremely disillusioned by what you see. So if you love wine… STOP READING NOW! KEEP BELIEVING IN UNICORNS! However, if you want to look behind the curtain… come on backstage.