How many operations per second, or perhaps more precisely FLOPS can I buy for £1, or if you prefer $1?

In comparison can the price and the difficulty be used to work this out for the BTC nework? I suspect not but I also suspect estimates to have been made. I think the number would be need to be reduced by some proportion to compensate for the way that the BTC cloud contains hardware designed only for mining BTC.

Is there a chart showing the price history for thease idearly together?