Bitcoin Plus has been the first alternative to BTC with the Bitcoin name, and has existed before all the recent forks of BTC: Bitcoin Cash, Bitcoin Gold, Bitcoin Diamond, Bitcoin SV, etc...
All those surrogate brands inundating the market since 2017 have not done good to Bitcoin Plus, but XBC has existed for many years prior to all of them.
Its proof of stake system is unique in that the staking % per year is fixed at 20%, irrespective of the cumulative time the wallet has been online or not. The staking weight of each address increases with time, even if the wallet is offline. A rare quality in the cryptocurrency space, this has proved to be a convenient and energy-saving feature.
Many wallets are not staking. Examples include cold storage addresses at exchanges (mainly), third-party service wallets like Coinomi, etc... Because of that, the addresses that are staking beat the inflation of the circulating supply, which we can guess must be around 15 % or slightly less.