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Adding up the numbers next to the different transaction types in the pie chart photos:
1st pie chart total transactions number is 316,739
2nd pie chart total transactions number is 433,064

That's a 36.7% increase.

Important to note, this does not include the complete numbers, since only the numbers for top 10 transaction types are given in each photo. But, still a good estimation, because the top 10 makes 99%+ of the total, looking at the pie chart.

More importantly, the difference of the totals is 116,325, while the difference in custom_jsons is 101,844.

So, assuming that ALL the additional custom_jsons are coming from splinterlands - that is probably not true -, splinterlands is responsible for 87.5% of the increase in transactions, and the other 12.5% is an increase for other Dapps.

Assuming that custom_jsons increased by 12.5% without splinterlands (same rate as the rest of the chain), splinterlands is responsible for 97,927 new transactions, or 84% of the new transactions.

Taking into account the transactions of type "transfer" made to buy splinterlands cards off the market, or even of type "vote" (for example all the votes on the splinterlands annoucement post that they're moving to hive) should also be done, but this comment is becoming too long and it wouldn't change the result by much.

Looks like @marki99 made the most elaborate answer I could have made.
I should hire him as a CM 😆