The perceived wisdom for smartphone app sales is that most of your sales tend to come in the first few days of release, when the app is most visible. Subsequent bumps are generally due to other factors, like releasing a free demo version or getting featured somewhere.
Fortunately, my overall best-selling app, Golf Solitaire, has bucked that trend. Here's a chart of sales since the game was released in May:
Sales have steadily increased month over month...a very nice trend. And you'll notice that I already have over 300 sales this month with about a week left.
I believe the highest rank it achieved was #3, before sliding back down to #9. But it never fell out of the top ten and as of this writing it has managed to climb back up to #4. I was resigned to see it slide down the rankings, replaced by newer apps, but it just keeps on keeping on, which is very satisfying.
I've added a mulligan feature (which unfortunately had a scoring bug), but that's now been fixed. People seem to love the game, and I hope it keeps on performing well throughout the year.