How do I convince my parents to allow me to get a facebook?

[me]

I'm 13 and i'm dying to have facebook my parents and brother both have one but try just won't let me theysais they've thought about it but still won't let me and it makes me feel like thy don't trust me. A 13 year old should be allowed some sort of freedoms right? What do I tell them? And don't say go behind their backs because they are on all the time and would find out an I'm trying to gain their trust not loose it