Location January May September North 6.5 6.0 4.3 North 7.1 6.6 5.0 North 8.3 7.1 4.9 North 6.6 8.0 4.5 North 7.3 7.5 4.1 South 7.3 7.5 4.3 South 9.1 8.0 3.9 South 8.0 7.7 3.5 South 8.1 8.0 7.1 South 8.4 8.3 3.6