highly significantP = 1.984 × 10 −14
BS and TCB did not differ significantly among years (BS: χ 2 = 1.0, df = 6, P = 0.9847; TCB: χ 2 = 0.3, df = 8, P = 1), whereas ST showed a highly significant year effect (χ 2 = 63.1, df = 2, P = 1.984 × 10 −14 ).