This title is quite misleading.
Hunger games now holds 3rd place for highest grossing weekend of any movie ever at $155million. It's behind Harry Potter and the Titanic I believe. Think like a man made $30 million it's first weekend to the Hunger games $15 million on it's 5th week. There is NO comparison in terms of sales. Pretty much anyone who wants to see the Hunger games already has so of course sales are decreasing.
This will more than likely be it's biggest weekend and it'll get knocked off the charts next week by something. It's a niche movie, for a niche market.