The Health Insurance Organisation (OAY)'s revenue from contributions to the General Health System (GeSY) amounted to €1.58 billion in 2023, while spending on health services amounted to €1.44 billion, Senior OAY Officer Angelos Tropis told CNA on Sunday, adding that the OAY fund is projected to be sustainable until 2031, citing the results of the latest actuarial study for the period 2022 - 2031.