That chart says that "PC games" amount for maybe $2-4bn in revenue in 2014 compared to console games' $20bn - that order-of-magnitude difference doesn't sit wel

That chart says that "PC games" amount for maybe $2-4bn in revenue in 2014 compared to console games' $20bn - that order-of-magnitude difference doesn't sit well with me at all. Where's the source data for this chart? I find it hard to believe that mobile games generate 5x more revenue than PC games.