Rendered video has a different time line, slower!

Hi, I feel I really must be missing something. Whenever I render my file in AE it renders it so it is slower than the actual file, with a longer duration than set in my time line. I have attached picture of the compostition settings and the export, so you can see the duration of the file is 3.18 sec but the export comes out at 3.58. This is happening multiple times now with different files.

Thanks