The data:

Since 2015, Sanders has raised more from small contributions (under $200) than any other Democrat, highlighting his grassroots support.

In both the 2016 and 2020 cycles, about 57% of his total fundraising came from small contributions. Joe Biden’s share of fundraising from small contributions so far is only 35%.

Sanders’ campaign says it took in 1.8 million donations during the fourth quarter — an average of $18.53.

The bottom line: Despite his age, and even after a heart attack and the insertion of stents this past fall, Sanders is surging again.