You can relate all your papers to each other, treat them as a whole to show your development as a writer, or you can compare them to each other to find out how they are all different, and how the writing of a previous paper helps the next. It is your preference.
To get started, here are a few things that I would recommend thinking about for your paper:
Have your writing habits changed over the time?
Which process---prewriting, drafting, responses, revision--- did you think the most important when you were doing the first paper? Has your feeling changed when it came to your second, third and fourth paper? Why?
Likewise, which process did you think the most difficult, or interesting at first, and whether/why it changed?
How did each paper develop in terms of its purpose and audience? And how did all the papers develop as a whole in terms of purpose and audience?
What global revisions did you make?
What did you learn while writing a particular paper? Were there difficulties? How did you resolve them?
Put these thoughts into your final analytical essay.
Remember: Merely answering the questions above is not what I want. I want
some original thoughts in these essays, and serious, thoughtful reflection.