Software Defined Networking (SDN) is in the process of revolutionizing the way of managing networks by providing a new way to support current and future services. However, by relocating the control functionality in a remote entity, the measurements' accuracy of the resources' utilization becomes more difficult, which complicates the decision making. Although there are previous works focusing on the problem of network management and measurement in SDN networks, only few proposed solutions have taken into consideration the tradeoff existing between statistics' polling frequency (i.e. generated overhead), and the accuracy of monitoring results (i.e. optimized resources' allocation). In this paper, we propose a new approach calculating accurately the bandwidth utilization while adapting the polling frequency according to ports/switches activity. The emulations' results under Mininet clearly demonstrate the effectiveness of the proposed solution, which outperforms existing works.