The majority of mining occuring with CPUs ended in late 2010, though the plurality may not have (i.e., there were more miners using CPUs but most mining was based on GPUs by the end of 2010). Most who remained using CPUs were pretty much squeezed out during Spring 2011.

GPUs could be purchased at retail, and were about the only technology that mattered from the beginning of 2011 into early-2012, so estimates could presume most hashing during that period was on GPUs. Efficiency of various GPU models varied widely, but most miners were using roughly similar hardware because of the combination of price, performance and availability.

FPGAs include custom FPGA designs targeted to Bitcoin (e.g., BFL) and others that were offering commercially available off-the-shelf products. Unit shipment numbers are generally not known. At their peak, FPGAs might have been less than a third of all hashing combined.

ASICs are just now impacting the hashrates, but in a few months will statistically completely displace all GPU and FPGA mining.