The expression 6.7\cdot1.45^t6.7⋅1.45 t 6, point, 7, dot, 1, point, 45, start superscript, t, end superscript models the number of billions of genetic sequence bases available in the public database of the Whole Genome Shotgun project ttt years since 200220022002. What does 1.451.451, point, 45 represent in this expression?