month	Mean_bill_Wash	Mean_bill_Dutch_Wadden_Sea
Jan	97.36	101
Feb	97.89	101.3
March	99.15	98.94
July	99.48	97.15
August	100.96	96.9
September	100.78	97.93
October	97.58	99.08
November	99.3	100.87
December	98.1	100.03