Apparently the rate of empty blocks on the Bitcoin (BTC) network is significantly declining, with only 71 empty blocks in the first 5 months of 2020, which accounts for only 0.3% of all Bitcoin (BTC) blocks. This is less than half of the empty block rate of 0.79% from the same period last year. 

An empty block is a Bitcoin (BTC) block which contains zero transactions aside from the coinbase transaction, which is the transaction that sends the block reward to the miner who found the block. 

Empty blocks are generally frowned upon, since empty blocks decrease the scalability of the network. Also, empty blocks defeat the purpose of mining in general, since miners are supposed to secure the network’s most recent transactions, rather than mining a block with no transactions.

The general reason that empty blocks happen is because during the short period of time that a miner is receiving the data for a new block, that miner will try to mine an empty block in order to not waste any resources during the block propagation delay. Indeed, the only way for a miner to make money while receiving data for a new block is to mine an empty block, since an empty block will not have any conflicting transactions with the new block. 

This mechanism perhaps explains why empty blocks are becoming less common. Newer mining rigs and faster network speeds are causing new blocks to be transmitted to miners faster than before, so there is less time during which miners are trying to find empty blocks. 

Thus, the rate of empty blocks on the Bitcoin (BTC) network is declining due to better technology, and perhaps this trend will continue long term. That being said, it is likely that there will always be some empty blocks no matter how good technology gets.