Known problems aside, I`m hardly surprised it`s not in the top ten.
1. It`s a sim. We all know, we are niche geeks.
2. That the US release doesn`t help much is even not surprising. No offense, but no Mustang and no P-47. `nuff said.
But it's a chart just showing sims sales? (the URL end bit is /genre/Simulations)