Information on the number and tax paid by non-domiciled taxpayers in the UK is contained within Table 1 of the Official Statistics publication “Statistics on Non-domiciled Taxpayers in the UK” found at: https://www.gov.uk/government/statistics/statistics-on-non-domiciled-taxpayers-in-the-uk
The latest year for which figures are available is 2014-15. Figures for subsequent years are intended for publication in the annual update made in July each year.
Information on the estimated number and tax paid of individuals that have claimed non-domiciled status for the first time can be found in the table attached for the previous five years up until 2014/15. Capital Gains Tax information on non-domiciled first time claimants cannot be released as this may risk the identification of individuals due to the small numbers involved.