On or before a date fixed by the city council but not later than 60 days prior to the beginning of each fiscal year, the mayor shall submit to the city council a proposed operating budget for the ensuing fiscal year. The budget shall be accompanied by a message from the mayor containing a statement of the general fiscal policies of the city, the important features of the budget, explanations of major changes recommended for the next fiscal year, a general summary of the budget, and such other pertinent comments and information. The operating budget and the capital budget hereinafter provided for, the budget message, and all supporting documents shall be filed in the office of the city clerk and shall be open to public inspection.