Food Stamps Usage continues to Rise

Based on the latest data from SNAP, 15% of Americans are now on Food Stamps.  This is a 100% increase since 2003.  If the economy is doing so well then why does food stamp usage continue to rise.  This continues to be a disturbing trend.  For example of food stamp usage were to rise another 100% in the next 10 years that would mean 30% of Americans (over 100 million people) would be using them.