What is the formula of *ESTIMATED* dividend yield?

Here: https://imgur.com/a/GFKkU8o

If you're going to say its based on last 12 months of dividends: Ok lets sum up the distributions of last 12 months and divide that by WHICH stock price?

Stock price of the last day of the month?

Average stock price of of last 12 months?

If average, based on the average of last days of the months? or is it a daily average of closing prices?

or is it something else?

Thanks!