Making Sense of Incomplete Data

The essence of the attached sheet is to try and get data about the value of non-oil exports by African countries where a bank has a presence. After obtaining this data, I intend to compare what share of the export business passes through the bank from customers that are in export trade and bank such proceeds with the bank. My greatest challenge stems from a dearth of data especially as it relates to the bank's customer's data. Despite my best efforts, getting this data has not been smooth. While some countries have provided this data for their customers, others are not forthcoming which is making comparison or analysis hard. Also, I initially wanted to get the National (Country) data monthly for 2021, and that relating to the bank's customers over the same period, However, the most reliable frequency for national data is annual most times, while for the bank's customers the most reliable frequency will be monthly. I need help making sense of it all despite gaps in the data. In particular how would you approach this task.