During this heat wave, our system performed very well and I’ll give you more details of that in a minute and later Tom will discuss the financial impacts from the weather and the recovery of the Michigan economy.
As you know, we settled the gas rate case for the second consecutive time. In part due to the relatively small size of the request. The larger electric rate case was approved at $118 million in line with the amount we self implemented. This case was primarily a recovery of investment costs representing 111% of the final order and lower operating cost, down $38 million from the prior order.
The Commission also adopted our sales forecast to reflect the 10% level of retail open access sales, up from 4% in prior rates. This adjustment increased our gross margin by $48 million. The commission approved a 10.3% ROE for both gas and electric.
Over the past few months, our system has been tested by the hot weather and it performed very well given the extreme conditions. On average, we have 10 days a year with temperatures of 90 degrees or warmer. So far this year, we’ve had 26 days with temperatures over 90 degrees and two days over 100 degrees. 10 of these days were in the second quarter, contributing $0.03 of earnings to the electric business.For the second consecutive year, we set a new peak load record. This year’s peak load was over 9000 megawatts surpassing the previous mark set last year in July by 2%. The trend line shows that peak demand has grown by 200 megawatts since 2006. Weather was a key factor as it was last year, but a growing economy also contributed. Weather adjusted sales are up 5% over the past three years led by industrial sales and are expected to grow about 1% annually over the next five years.