I have a thirteen year old daughter and worry like mad if she's out late. Not because I don't trust her, but because I worry about her being mugged or even raped. I have explained this to her, but she doesn't see the world as a bad place and thinks I worry needlessly. Yet every day I read about women being raped and muggers beating up grannies.
I went for a compromise in the end, and only let her out if she is with someone and then only until 9 o'clock during the week or 10 o'clock at weekends. During the week she must finish any homework before going out. She isn't allowed to leave the estate we live on, has to have her mobile phone with her and I have to know where she is going. I have a list of all her friends addresses and phone numbers so I can contact her in an emergency.
I know this may sound a little OTT, but she gets to go out and I have some peace of mind.