Suspicious Voting

President Trump has been severely criticized for suggesting there was fraud in the 2020 election. Here is a chart listing the number of popular votes for each candidate in the last four presidential elections...

Note that in three of the four elections including the last one, the Democrat candidates consistently received around 66 million votes each. However, in 2020 the year of the pandemic when states extended voting hours and expanded early voting via absentee ballots and ballot boxes, Biden got 81 million votes. I do not consider myself to be a conspiracy theorist, but I have to wonder how many of those 15 million additional votes might be due to fraud?