Prospectus excerpt:  We are offering 2,400,000 shares of our 7.875% Series D Cumulative Redeemable Preferred Stock, which we refer to as the Series D Preferred Stock, or the Shares. This is the initial issuance of the Series D Preferred Stock. When, as, and if authorized by our board of directors and declared by us, distributions on the Series D Preferred Stock will be payable quarterly in arrears on or about January 30, April 30, July 30, and October 30 of each year at a rate per annum equal to 7.875% per annum of the $25.00 liquidation preference. Distributions on the Shares are cumulative. The first distribution on the Series D Preferred Stock sold in this offering will be paid on July 30, 2021, will cover the period from, but not including, May 21, 2021 to, but not including, July 30, 2021 and will be in the amount of $0.377344 per share.