scatter diagram for fatigue analysis

I have scatter diagram with total number of occurrences 175320 waves. It is indicated a note that these records are "Hourly event number of occurrence - reference period: 20

years". My question, what does this note mean? should we multiply the scatter records to factor?

Scatter diagram file is attached.

Thanks

LGK-025126-Appendix_C_Hs_Tp_Numb_Tables.xlsx