pre_text: entergy mississippi , inc . management's financial discussion and analysis other regulatory charges ( credits ) have no material effect on net income due to recovery and/or refund of such expenses . other regulatory credits increased primarily due to the under-recovery through the grand gulf rider of grand gulf capacity charges . 2003 compared to 2002 net revenue , which is entergy mississippi's measure of gross margin , consists of operating revenues net of : 1 ) fuel , fuel-related , and purchased power expenses and 2 ) other regulatory charges ( credits ) . following is an analysis of the change in net revenue comparing 2003 to 2002. .
post_text: the increase in base rates was effective january 2003 as approved by the mpsc . gross operating revenue , fuel and purchased power expenses , and other regulatory charges ( credits ) gross operating revenues increased primarily due to an increase in base rates effective january 2003 and an increase of $ 29.7 million in fuel cost recovery revenues due to quarterly changes in the fuel factor resulting from the increases in market prices of natural gas and purchased power . this increase was partially offset by a decrease of $ 35.9 million in gross wholesale revenue as a result of decreased generation and purchases that resulted in less energy available for resale sales . fuel and fuel-related expenses decreased primarily due to the decreased recovery of fuel and purchased power costs and decreased generation , partially offset by an increase in the market price of purchased power . other regulatory charges increased primarily due to over-recovery of capacity charges related to the grand gulf rate rider and the cessation of the grand gulf accelerated recovery tariff that was suspended in july 2003 . other income statement variances 2004 compared to 2003 other operation and maintenance expenses increased primarily due to : 2022 an increase of $ 6.6 million in customer service support costs ; and 2022 an increase of $ 3.7 million in benefit costs . the increase was partially offset by the absence of the voluntary severance program accruals of $ 7.1 million that occurred in 2003 . taxes other than income taxes increased primarily due to a higher assessment of ad valorem and franchise taxes compared to the same period in 2003 . 2003 compared to 2002 other operation and maintenance expenses increased primarily due to : 2022 voluntary severance program accruals of $ 7.1 million ; and 2022 an increase of $ 4.4 million in benefit costs. .
table: (In Millions)
table: 2002 net revenue $380.2
table: Base rates 48.3
table: Other (1.9)
table: 2003 net revenue $426.6
question: Analyse this data from a financial earnings document. what is the increase in operation and maintenance expenses as a percentage of net revenue in 2003?