The reason you aren't getting the right answer is because you are calculating the percent, while the problem asks for the percent increase.
When looking for the percent increase, you must first subtract the two numbers to find how much it increased by. Then you find the percent. The formula looks like this:
(New Number - Original Number) / (Original Number)
For your specific example it would look like this:
(3715393 - 1331046) / 1331046
I hope this helps