accounting for approximately 9% of our total square footage. We have also identified approximately 625,000 square feet of additional redevelopment opportunities embedded in our existing assets.  In addition, at year-end, we had six properties under development comprising a total of 358,000 square feet, and a development land bank together with expansion opportu- nities embedded in our existing asset base approximating 3,719,000 square feet.  During 2004, we also benefited from external growth with the closing of approxi- mately $374 million in acquisitions, adding approximately 1.6 million square feet to our asset base. Our external growth strategies, once again, remained highly selective and focused on our key life science cluster markets as we continued to expand, strengthen, and enhance our strategic franchise.  In a very cost-conscious environment, we have continued to focus on effectively controlling the costs of our operations and have continued to maintain strong operating margins, which approximated a very healthy 79% during 2004, and have maintained strong year-end interest and fixed charge coverage ratios of 4.53 and 2.70, respectively. During 2004, we sold one property at a net gain of approximately $1.6 million.This sale reflects our program to critically evaluate the strategic value of all of our properties on an ongoing basis, and sell selected properties when appropriate so that capital may be pru- dently recycled.This sale provided more than $5 million in recycled capital to be put to work on more strategic opportunities for future growth. We continued to execute our strategy of maintaining a strong, conservative, flexible and transparent capital structure. We have experienced solid growth while steadfastly maintaining balance sheet strength and flexibility. FFO for the year 2004 was approxi- mately $86.6 million on revenues of approximately $183.3 million. Our debt to total market capitalization as of December 31, 2004 approximated 42%.  O P E R AT I O N O U T R E A C H A N D G L O B A L D I S A S T E R S We were deeply saddened by the devastation caused by the earthquake and subsequent tsunami in South Asia in late December 2004. Our response was immediate and focused. We supported Doctors Without Borders and their important work in the disaster regions. Beyond our immedi- P 6