@Liz244,
Goto section "performance" (from main menu at top), choose tab "earnings".
Scroll down and click on the year 2018 (underneath the graphic), then the amount of occupied nights in 2018 will be on the list beneath it.
You can also download CSV files (regarding selected periods) from Transaction History page, to be loaded into a spreadsheet , to create custom statistics.
And you can use the filter option in the "reservations list" to select all reservations and sum up the amount of nights (displayed under each reservation).
Which can also be done by downloaded a CSV file (option "export"), so then the spread sheet can sum up....
Best regards,
Emiel