For the fifth time in four years, your monthly power bill dropped. This month, Tampa Electric’s residential bills dropped by $4.32, to $102.58 a month for 1,000 kilowatt-hours (kWh). That puts Tampa Electric’s bills at about 14 percent below the national average – which was $119 per month in May 2012, according to the Energy Information Administration. Tampa Electric continues to have one of the lowest residential rates in Florida.…