You can do something much simpler based on the 9/30/15 & 12/31/20 financials and the shareholder letter.
456 loan repayments
(154) funding of new loans
(22.2) dividends paid
(13.5) increase in cash balance
(170) liabilities paid
(21.3) investment in partnerships
That leaves $115 of missing cash, which presumably went to pay expenses (my dividends are also probably off because they exclude the 10/15 & 11/15 amounts paid)..
Over 5.25 years, the $115 works out to $22 per year.
2015 annualized expenses were $18, so I’m not too far off. Legal fees, increased accounting fees, interest before the debt was repaid, etc could make up the difference.