Could someone explain how the economic woes are not the fault of Bush and republicans?

when they had control of govt lock stock and barrel for all that time? In other words, if that ped all those laws and made all those policies during all that time, and it looks like we face a serious crisis as Bush himself admits..as most all politicians admit, then should not Bush and his GOP rubber stamp congress bear the brunt of the blame?..say at least 70%?