growing your down payment of $40,000 into free and clear property ownership

[lavazza]

Был куплен дом, стоимостью 200,000, из них 40,000 было заплачено из своих денег, а 160,000 было взято в кредит.
Не пойму, что в этом контексте означает "grow into".
Контекст:
Say that after 20 years of ownership, your rent collections cover operating expenses, pay off the property’s mortgage balance of $160,000, and give you a net annual income yield of zero. At the end of year 20, you sell this property for $200,000, your original purchase price, but by growing your down payment of $40,000 into free and clear property ownership 20 years later, you received a return on your investment of nearly 8.5 percent.

[eu_br]

первоначальный взнос "вырос" в полное право собственности.

[lavazza]

Спасибо!