I am sure this number will go up as more validators come online and users get their nodes registered.

Only a portion of the transactions will increase as more validators come online. It works similarly to Hive witnesses in that one SPS validator is chosen to validate the SPS transactions in every Hive block. The chances that a particular validator will be chosen to validate a specific Hive block is proportionate to the amount of SPS stake voting for them (like with the "backup" Hive witnesses).

All that just means that the SPS validator network as a whole will broadcast one custom_json operation for each Hive block as part of the main validation process and that will not change no matter how many validators are running on the network.

So in your data, you showed 2,153 sm_sps transactions in 1,708 Hive blocks. 1,708 of those transactions were the validation transactions for each block and 445 were other transactions, such as validators that don't get assigned a block "checking in" to prove the software is running so they can earn rewards, and I think there are some other things like price feed updates.

The one transaction per block will not change no matter how many validators are running, but the other transactions will increase proportionally as more validators come online.