How many blocks have no unspent transaction outputs?
The page Bitcoin UTXO Stats has a visualization of the number of UTXOs in each block (image with orange pixels). 

Each pixel of the image represents a block, and the color of the pixel indicates how many UTXOs can be found in that block (black pixels indicate a few UTXOs whereas orange ones indicate lots of UTXOs). Hovering over a pixel shows data about the specific block and clicking on a pixel redirects to the block page on blockchain.info.