Thanks @tarazkp for calling ;-)
It's actually in 0.01% steps, starting from HF16, and interval is not in days, it's in blocks.

HARDFORK 16 at block 7353249

Starting with the network’s 16th hard fork in December 2016, Steem began creating new tokens at an
annual inflation rate of 9.5%. The inflation rate decreases at a rate of 0.01% every 250,000 blocks, or
about 0.5% per year.

So it seems that next, 98th decrease will be after block 31853249, that is in a little bit more than 3 days and 5 hours from now.