~40% of people don't get enough vitamin D [1]. It's not useful to categorize it as some trend, based on people just not following general recommended dosing (with more precise dosing depending entirely on personal sun exposure and skin color).
edit: As an office worker, I take 10k IU per day when I'm entirely indoors (most of the time), but vary it based on sun exposure. I based this on recent studies, and have my doctors approval with an exactly center-of-the-nominal-range vitamin D serum level.