Today's difficulty change marks the first time since the introduction of Bitcoin mining ASICs that the network difficulty has dropped. Network difficulty went from 40,300,030,328 to 40,007,470,271 which is a loss of 0.73 percent. The first difficulty decrease happened in 2011 when pool operators discovered the existence of botnet miners for the first time and banned several. Other difficulty decreases happened during the GPU mining era when price dips made the energy cost of mining unprofitable in the near term. Since January 2013, the month before the introduction of the first commercial ASIC miners by Avalon mining difficulty has increased by more than 1,300,000 percent.