No more replies from a couple of my representatives!

Well, I've lost touch with one of my U.S. Senators and my U.S. Representative. Not that they have stopped sending me multiple informational emails from their respective offices each week... Since last summer, all three of my federal representatives have just about stopped sending me any replies at any of my letters to them! Is anyone having the same responses lately?

This won't stop me at all from sending those personal letters from their website contact forms; nor, will I stop participating in selected public interest group "contact your Congressman" drives. However, they will know how increasingly dismayed I am as their owner, the American taxpayer.