As an example of financial forensics, in State of Arizona v$.$ Wayne James Nelson, Mr$.$ Nelson was accused of trying to defraud the state of nearly $$2$ million. Nelson, a manager in the office of the Arizona State Treasurer, argued that he wasn't trying to steal the money but had diverted actual vendor invoice amounts to a bogus vendor only to demonstrate the absence of safeguards in a new computer system. What proportion of the checks had a leading digit of $7,8,$ or $9?$