It is all calculated on the debt ratio.
When the STEEM/SBD debt ratio is between 3% and 5% we will receive no Steem and all rewards will be in SBD.
When the STEEM/SBD debt ratio is between 2% and 5% it will be a mix of SBD and Steem depending on percentages.
When the STEEM/SBD debt ratio is more than 9%-10% we will receive 100% Steem like we had recently.
This has just changed recently during the hardfork.