Fan mail info!!!!?

On average how long to celebs take to respond to fan mail? Also put your fan mail experiences here. Also put celebs and athletes that have either responded or not responded. I sent out a TON of celeb letters about 6 months ago to my favorite celebs...and only 3 responded. Should I be worried? And yes, these were the right addresses because I got them off the the celebs offical website or in disney magizine. One of the responses was a autographed photo, one was a postcard saying thank you, and one was a advertisment to pay to subsribe to their website. Will more responses come or not? PLEASE HELP!