RNA HELP!!!!!!!!!!!!!!!!?

Most of the bacterial DNA codes for mRNA, and most of the RNA produced by the cell is mRNA. Yet ysis of teh RNA content of a cell reveals that, typically, rRNA is about 80 percent of the cellular RNA and tRNA makes up most of the rest. Only about 2 percent is normally mRNA. How do you explain these findings? What do you think the functional explanation might be?