The proposed budget of each state agency shall show the amounts required for operating expenses separately from the amounts required for permanent improvements. The overall budget shall show, separately by each source, the estimated amount of general fund revenue and of special fund revenues of general fund agencies. The total proposed expenditures in Part 1 of the overall budget shall not exceed the amount of estimated revenues that will be available in the general and special funds for appropriation or use during the succeeding fiscal year, including any balances other than unencumbered balances in general funds that will be on hand in the general and special funds at the close of the then current fiscal year. The total proposed expenditures from the State General Fund in Part 1 of the overall budget shall not exceed ninety-eight percent (98%) of the amount of general fund revenue estimate for the succeeding fiscal year. However, for fiscal years 2010, 2011, 2012, 2016 and 2017 only, the total proposed expenditures from the State General Fund in Part 1 of the overall budget shall not exceed one hundred percent (100%) of the amount of the general fund revenue estimate for the succeeding fiscal year, and for fiscal year 2018, the total proposed expenditures from the State General Fund in Part 1 of the overall budget shall not exceed ninety-nine percent (99%) of the amount of general fund revenue estimate for the succeeding fiscal year. The general fund revenue estimate shall be the estimate jointly adopted by the Governor and the Joint Legislative Budget Committee. The Legislative Budget Office may recommend additional taxes or sources of revenue if in its judgment those additional funds are necessary to adequately support the functions of the state government.