"Fixed-dollar arrangements now account for 47% of plans in [this] Survey. While previously popular among larger plans, that is, those with $1 billion or more in assets, fixed-dollar arrangements are now increasingly prevalent among mid-size plans with $100 million to $500 million in assets ... [T]he recordkeeping fees for half of all retirement investment accounts are still calculated using pricing models based on assets within the plan. In addition, recordkeeping fees include some element of revenue sharing for most plans."