if you are in a development, most likely there has been an increase in subscribers. In other words, the signal is split that many more times. They will/should come out and install an amplifier on your line (or before it).
Otherwise, the drop cable from the pole to your house could be damaged (but that rarely happens.) Try not to let them talk you into digging up your yard to replace the drop, then having a cable on your lawn for 6 weeks before they show up to re-bury it, only to find that was not the problem. (been there done that)