Currently none, as @tipU has enough own STEEM POWER to cover all existing investments. Around 800 SP left so new investments for total of 800 STEEM or 1120 SBD can be covered.
Once those 800 SP will be "used", any new investments will require @tipU to buy STEEM and power up. So there's no defined percentage (%) of investments converted to STEEM POWER, it depends on how many SBD/STEEM is invested compared to @tipU STEEM POWER. Hope this helps :)