Assume the annual rate of change in the national debt of a country (in billions of dollars per year) can be modeled by the function D'(t) = 835.85 + 818.12t- 195t-+ 18.2+3 where t is the number of years since 1995. By how much did the debt increase between 1996 and 2004? The debt increased by $ billion (Round to two decimal places as needed.)