But do you know for a fact that it lets through a larger proportion of the spam sent to it, or are you just noticing that it gets a larger total volume of spam

But do you know for a fact that it lets through a larger proportion of the spam sent to it, or are you just noticing that it gets a larger total volume of spam than the others? Because if it's the latter, that could be an effect of more spam being sent to your gmail than to your other accounts.