I have naturally brown hair, it's the second most common hair color after black
Brown hair is lovely! I didn't realize it was that popular! Are there a lot of shades of brown hair?
There are, it varies from light brown to almost black. Mine is closer to almost black so it makes it hard for me to change my color up without bleaching it.
Mine is a more like a dark blonde. I've always wanted to dye my hair brown though!
Go ahead and dye it! 75% of women and 15% of men report having dyed hair.
75% of women?! Wow! I would have never guessed it would be that high! Is there a specific term that refers to people with brown hair?
They're often referred to as "brunette" which in french is the feminine from of "brunet", the diminutive of "brun" (brown)
That's right, thank you! I couldn't think of the word! Are there many famous brunettes? 
Oh lots! It's a common haircolor of people from Europe and the US and also some populations in the Greater Middle East.