Just to chime in, vitamin D deficiency is extremely common:

Recent large observational data have suggested that ~40% of Europeans are vitamin D deficient, and 13% are severely deficient [2]

Study with source

Vitamin D deficiency has also been linked to dementia and other bice diseases. I bet 15 minutes sunlight won’t cut it and sunbathing gives you skin cancer in the long run, so get some supplements people!