Ask HN: What is your goto site for market statistics? For ex,number of day cares

What sites do you use for market research? Is it random news articles pieced together or do you know specific sites. For example, if you want to know how many child day cares exist and how much they pay the teachers, what websites do you use to find the data? Or for example, how many iphone cases/covers have been sold is last one year? Any site dedicated to statistics/discussions like this?