There's a "statistic" section on front page for such a information.
I noticed there were two topics from this subject made in Pelit-forum (Pelit--> Finlands largest gaming magazine, but not big if compared to its global "colleagues"). I saw that some people kept telling that Aquaria is the only game worthy of 20-25 $ in that package, but they have had some difficulties with their game activations and with feedback related to that problem (I guess this is the old problem related to Plimus and its way of doing things). Thats why they paid low prices.
I'm not too sure if I should post such a things here, but I found that interesting.