Blizzard recently released some interesting statistics about Hearthstone Arena play.
The infographic below is for the Americas only but you can find more for other regions.
I’ve mostly been playing constructed but keeping up with the meta has been nearly impossible with my free-to-play account (F2P). With the exception of the Welcome Bundle in September, I haven’t purchased any packs or used money to unlock solo adventures. I think I’ll be switching to Arena play since it’s easy to earn the gold by completing quests.