To Fill Data in a Series
1. Enter the beginning of a series into to at least the first two cells. Ex: If using years, enter 2020 and 2021 into the first two cells.
2. Highlight the data you just entered and a 'Fill Handle' 
will appear (you will see a black box in the lower-left hand side of the last selected cell).
will appear (you will see a black box in the lower-left hand side of the last selected cell).3. Click and drag that 'Fill Handle' down or to the right to the last cell you wish to have data entered into and it will automatically fill in the rest of the data.
If you want to automatically fill in data that is not sequential, such as counting by 2s, type the first number in the first row, then type the second number in the scale in the second row and then highlight both cells. Then click and drag the 'Fill Handle' down or to the right to the last cell you wish to have data entered into and it will automatically fill in the rest of the data.