A $30-$year security has a price of $$19,759\mathrm{.}12.$ The security pays $$1,000$ at the end of each of the next $10$ years, and then it pays a different fixed cash flow amount at the end of each of the following $10$ years. Finally, in years $21-30$ it pays $$4,000$ per year at year end. Interest rates are $8\mathrm{.}0\%.$ What is the annual cash flow amount between years $11$ and $20?$