getnetworkhashps
Pass in [blocks] to override # of blocks, -1 specifies since last difficulty change.
Pass in [height] to estimate the network speed at the time when a certain block was found.
Argument #1-nblocks
Type: number (int), Optional
Default=120
Description: The number of previous blocks to calculate estimate from, or -1 for blocks since last difficulty change.
Argument #2-height
Type: number (int), Optional
Default=-1
Description: To estimate at the time of the given height.
Result
Type: number (int)
Description: Hashes per second estimated