This was a surprisingly difficult question to answer!
And the answer is, I really don't know.
I have a custodial IRA I inherited, my wife's 401k, Vanguard accounts, 2 Vanguard Roth accts, a Vanguard IRA, 3 different 401Ks at Fidelity, and two more 401Ks elsewhere.
A few give you an online year-to-date statement that clearly says the amount of dividends received.
A few let you see the dividend $ as they are paid but you have to add them all up yourself.
And a few never mention dividends at all. They just show account balance.
I was able to identify $14,237 in dividends but the ratios of dividends to account balance are extremely divergent, so I suspect some dividends are just included in "market gains". Example dividend percentages are 1.85%, 1,75%, 1.93%, 0.10%, 0.53%. Simplifying this is one of my jobs next year after we fire.