LONDON--Investment manager 3i Group PLC (III.LN) said Thursday it had another year of strong performance, recording a 3.9% rise in total assets under management during the fiscal year to end-March. 3i Group--a U.K.-based company which focuses on mid-market private equity, infrastructure and debt management--said total assets under management rose to 14.0 billion pounds ($20.09 billion) from GBP13.47 billion a year earlier.