Network Slicing aims for creating isolated virtual networks called \emph{slices} on the same physical infrastructure. The network resources are allocated to the slices according to their specific service requirements. This paper proposes Dynamic User Count Aware (DUCA) method for allocating radio access network resources to slices. Different than previous work DUCA accounts for the slice user count for deciding the amount of slice resources. To this end, DUCA increases the number of granted users in the network, increases the fairness of resource allocation towards slices with large number of users and small user bandwidth demands. The slices with small number of users and large bandwidth demands have better fitting resource allocation to their requests increasing the efficiency. We evaluate DUCA using simulation and compare its performance two to relevant previous resource allocation frameworks. We observe that DUCA achieves the above benefits with comparatively better results.