ValidatorHistoricalRewards represents historical rewards for a validator.
Height is implicit within the store key.
Cumulative reward ratio is the sum from the zeroeth period
until this period of rewards / tokens, per the spec.
The reference count indicates the number of objects
which might need to reference this historical entry at any point.
ReferenceCount =
number of outstanding delegations which ended the associated period (and
might need to read that record)
number of slashes which ended the associated period (and might need to
read that record)
one per validator for the zeroeth period, set on initialization
ValidatorHistoricalRewards represents historical rewards for a validator. Height is implicit within the store key. Cumulative reward ratio is the sum from the zeroeth period until this period of rewards / tokens, per the spec. The reference count indicates the number of objects which might need to reference this historical entry at any point. ReferenceCount = number of outstanding delegations which ended the associated period (and might need to read that record)