A fund had a value of $66.3 million on 1 January 2018. A net cash flow of $27.3 million was received on 1 July 2018 and a further net cash flow of $24.6 million was received on 1 January 2019. The fund had a value of $68.0 million on 30 June 2018 and a value of $99.5 million on 31 December 2018. The value of the fund on 1 January 2020 was $142.4 million. What is the linked internal rate of return per annum over the two years from 1 January 2018 to 31 December 2019, using sub intervals of a calendar year?