I am not sure what the percentage is. However, it is critical to have a very strong employee benefit package right out of the box. This is most important if you want to attract the best emplyees. That said, Obama care might work for those with pre-existing conditions if a group plan cost is prohibitive.
Since employees are motivated by factors, it is important to address these factors based on the type of employees you would like to attract. For example, some employees are just interested in their job. They are motivated by basic incentives. Then there are managerial types. They could be motivated by a discretionary bonus. Then there are the "Gift of God" types. These are employees that are very driven, they deliver big time, they treat the business as their own, they bring in quality sales. They hit the ground running and they want a piece of the action.
I would like to encourage you to hire the "Gift of God" types as they are what all start-ups need. They deliver cash flow. Cash is king!. Engage the services professional Industrial Organization professionals to help you assess and build an initial starting team. This could make all of the difference between success and failure.